the present disclosure is here described in detail with reference to embodiments illustrated in the drawings , which form a part here . other embodiments may be used and / or other changes may be made without departing from the spirit or scope of the present disclosure . the illustrative embodiments described in the detailed description are not meant to be limiting of the subject matter presented here . “ catalyst ” refers to one or more materials that may be of use in the conversion of one or more other materials . “ substrate ” refers to any material of any shape or configuration that yields a sufficient surface area for depositing a washcoat and / or overcoat . “ washcoat ” refers to at least one coating including at least one oxide solid that may be deposited on a substrate . “ milling ” refers to the operation of breaking a solid material into a desired grain or particle size . “ co - precipitation ” may refer to the carrying down by a precipitate of substances normally soluble under the conditions employed . “ calcination ” refers to a thermal treatment process applied to solid materials , in presence of air , to bring about a thermal decomposition , phase transition , or removal of a volatile fraction at temperatures below the melting point of the solid materials . “ rare metals ” refers to chemical elements in the lanthanides group , scandium , and yttrium . “ oxygen storage material ( osm )” refers to a material able to take up oxygen from oxygen rich streams and able to release oxygen to oxygen deficient streams . “ oxygen storage capacity ( osc )” refers to the ability of materials used as osm in catalysts to store oxygen at lean and to release it at rich condition . “ conversion ” refers to the chemical alteration of at least one material into one or more other materials . “ adsorption ” refers to the adhesion of atoms , ions , or molecules from a gas , liquid , or dissolved solid to a surface . “ desorption ” refers to the process whereby atoms , ions , or molecules from a gas , liquid , or dissolved solid are released from or through a surface . “ r value ” refers to the number obtained by dividing the reducing potential by the oxidizing potential of materials in a catalyst . “ rich condition ” refers to exhaust gas condition with an r value above 1 . “ lean condition ” refers to exhaust gas condition with an r value below 1 . “ air / fuel ratio ” or “ a / f ratio ” refers to the weight of air divided by the weight of fuel . the present disclosure may provide enhanced oxygen storage capacity with improved thermal stability properties , which may include a chemical composition substantially free from rare metals . it is an object of the present disclosure to provide an oxygen storage material ( osm ) which may include cu — mn spinel as osm and variations of cu — mn ratios with a suitable doped zirconia , including niobium - zirconia support oxide for osm applications , having an enhanced oxygen storage capacity and optimized thermal stability . according to an embodiment , the disclosed cu — mn spinel as osm with a suitable doped zirconia , including nb 2 o 5 — zro2 support oxide may be applied as washcoat layer , employing a suitable cordierite ceramic substrate to measure osc property and thermal stability . the subject osm may be prepared using co - precipitation method or any other preparation technique known in the art . the preparation of cu — mn spinel as osm may begin by milling nb 2 o 5 — zro 2 support oxide to make aqueous slurry . the nb 2 o 5 — zro 2 support oxide may have nb 2 o 5 loadings of about 15 % to about 30 % by weight , preferably about 25 % and zro 2 loadings of about 70 % to about 85 % by weight , preferably about 75 %. the cu — mn solution may be prepared by mixing an appropriate amount of mn nitrate solution ( mnno 3 ) and cu nitrate solution ( cuno 3 ), where the suitable copper loadings may include loadings in a range of about 10 % to about 15 % by weight . suitable manganese loadings may include loadings in a range of about 15 % to about 25 % by weight . the next step is precipitation of cu — mn nitrate solution on nb 2 o 5 — zro 2 support oxide aqueous slurry , which may have added thereto an appropriate base solution , such as in order to adjust the ph of the slurry to a suitable range . the precipitated slurry may be aged for a period of time of about 12 to 24 hours under continued stirring at room temperature . according to principles in the present disclosure , cu — mn spinel as osm may be used in wc layer for application on substrate , using a suitable cordierite material with honeycomb structure , where substrate may have a plurality of channels with suitable porosity . the osm in form of aqueous slurry of cu — mn / nb 2 o 5 — zro 2 may be deposited on the suitable substrate to form a washcoat employing vacuum dosing and coating systems . in the present disclosure , a plurality of capacities of wc loadings may be coated on suitable substrates . the plurality of wc loading may vary from about 60 g / l to about 200 g / l , in this disclosure particularly about 120 g / l . subsequently , after deposition on substrate of the suitable loadings of cu — mn / nb 2 o 5 — zro2 osm slurry , the wc may be treated . according to embodiments in the present disclosure , treatment of the wc may be enabled employing suitable drying and heating processes . a commercially available air knife drying systems may be employed for drying the wc . heat treatments may be performed using commercially available firing ( calcination ) systems . the treatment may take from about 2 hours to about 6 hours , preferably about 4 hours , at a temperature within a range of about 550 ° c . to about 650 ° c ., preferably at about 600 ° c . a suitable osm deposited on substrate may have a chemical composition with a total loading of about 120 g / l , including a cu — mn spinel structure with copper loading of about 10 g / l to about 15 g / l and manganese loading of about 20 g / l to about 25 g / l . according to principles in the present disclosure , the disclosed composition of cu — mn spinel as osm may be subjected to testing under isothermal oscillating condition to determine the o 2 and co delay times and osc properties at a selected temperature . a set of different o 2 and co delay times may be obtained when a range of temperatures may be chosen to further characterize the osc properties of the osm material . in order to check the thermal stability of the disclosed cu — mn spinel as osm , samples may be hydrothermally aged employing about 10 % steam / air at about 900 ° c . and about 1000 ° c . for about 4 hours . test results may be compared with a plurality of existing fresh samples . according to principles in the present disclosure , in order to determine the optimal composition of cu — mn spinel , for optimum oxygen storage capacity , different testings may be performed for determination of o2 and co delay time as representative of oxygen storage property of disclosed osm systems . fresh and aged disclosed osm samples with different variations of cu and mn ratios may be evaluated in accordance with the following test procedures : cu 0 . 5 mn 2 . 5 o 4 spinel with zro 2 — nb 2 o 5 support oxide as osm preparation of example # 1 as osm may include samples of cu — mn spinel as described above using cu 0 . 5 mn 2 . 5 o 4 composition with zro 2 — nb 2 o 5 support oxide , having a cu loading 6 . 6 g / l , and mn loading of 28 . 2 g / l . the total loading of wc is 120 g / l . cu 0 . 75 mn 2 . 25 o 4 spinel with zro 2 — nb 2 o 5 support oxide as osm preparation of example # 2 as osm may include samples of cu — mn spinel as described above using cu 0 . 75 mn 2 . 25 o 4 composition with zro 2 — nb 2 o 5 support oxide , having a cu loading of 9 . 8 g / l , and mn loading of 25 . 4 g / l . the total loading of wc is 120 g / l . cu 1 . 0 mn 2 . 0 o 4 spinel with zro 2 — nb 2 o 5 support oxide as osm preparation of example # 3 as osm may include samples of cu — mn spinel as described above using cu 1 . 0 mn 2 . 0 o 4 composition with zro 2 — nb 2 o 5 support oxide , having a cu loading of 13 . 0 g / l , mn loading of 22 . 4 g / l . the total loading of wc is 120 g / l . testing of the osc property of the disclosed cu — mn spinel as osm with variations of cu — mn ratios various spinel compositions ) may be performed under isothermal oscillating condition to determine o 2 and co delay times , the time required to reach to 50 % of the o 2 and co concentration in feed signal . testing may be performed for fresh and hydrothermally aged samples of the disclosed osm samples to compare oxygen storage property of the disclosed osm . the osc isothermal test may be carried out at temperature of about 575 ° c . with a feed of either o 2 with a concentration of about 4 , 000 ppm diluted in inert nitrogen ( n 2 ), or co with a concentration of about 8 , 000 ppm of co diluted in inert n 2 . the osc isothermal oscillating test may be performed in a quartz reactor using a space velocity ( sv ) of 60 , 000 hr - 1 , ramping from room temperature to isothermal temperature of about 575 ° c . under dry n 2 . at the temperature of about 575 ° c ., osc test may be initiated by flowing o 2 through the osm samples in the reactor . after 2 minutes , the feed flow may be switched to co to flow through the osm samples in the reactor for another 2 minutes , enabling the isothermal oscillating condition between co and o 2 flows during a total time of about 1 , 000 seconds . additionally , o 2 and co may be allowed to flow in the empty test reactor not including the disclosed osm . subsequently , testing may be performed allowing o 2 and co to flow in the test tube reactor including fresh samples of the disclosed osm and observe / measure the osc property of the disclosed osm . as the disclosed osm may have osc property , the osm may store o 2 when o 2 flows . subsequently , when co may flow , there is no o 2 flowing , and the o 2 stored in the disclosed osm may react with the co to form co 2 . the time during which the osm may store o 2 and the time during which co may be oxidized to form co 2 may be measured . according to principles in the present disclosure , the osc test may assist in analyzing / measuring an elemental carbon balance and illustrate what occurs during flowing of co through the osm samples , the desorption of o 2 which may be stored in the disclosed osm , and the formation of co 2 in absence of a o 2 stream . fig1 shows osc isothermal oscillating test 100 of fresh samples of cu — mn spinel of example # 1 as osm at 575 ° c ., which may include samples of cu 0 . 5 mn 2 . 5 o 4 with zro 2 — nb 2 o 5 support oxide . the samples employed for the investigation described below may be prepared as per example # 1 to determine co and o2 delay time at temperature of about 575 ° c ., according to an embodiment . in fig1 , curve 102 ( double - dot dashed graph ) shows the result of flowing 4 , 000 ppm o 2 through an empty test reactor which may be used for osc isothermal oscillating test 100 . curve 104 ( dashed graph ) depicts the result of flowing 8 , 000 ppm co through the empty test reactor , curve 106 ( single - dot dashed graph ) shows the result of flowing 4 , 000 ppm o 2 through the test reactor including the disclosed osm , and curve 108 ( solid line graph ) depicts the result of flowing 8 , 000 ppm co through the test reactor including the disclosed osm . it may be observed in fig1 that the o 2 signal in presence of the disclosed cu — mn spinel as osm , as shown in curve 106 , does not reach the o 2 signal of empty reactor shown in curve 102 . this result indicates the storage of a large amount of o 2 in the disclosed osm samples . the measured o 2 delay time , which is the time required to reach to an o 2 concentration of 2 , 000 ppm ( 50 % of feed signal ) in presence of the osm sample , is about 45 . 67 seconds . the o 2 delay time measured from osc isothermal oscillating test 100 indicates that the disclosed osm samples have significant osc properties . similar result may be observed for co . as may be seen , the co signal in presence of disclosed osc showed in curve 108 does not reach the co signal of empty reactor shown in curve 104 . this result indicates the consumption of a significant amount of co by the disclosed osm sample and desorption of stored o 2 for the conversion of co to co 2 . the measured co delay time , which is the time required to reach to a co concentration of 4000 ppm in the presence of osm sample is about 44 . 55 seconds . the co delay time measured from osc isothermal oscillating test 100 shows that the disclosed osm samples have significant osc properties . the measured o 2 delay time and co delay times may be an indication that the disclosed cu — mn spinel as osm , substantially free from rare metals , may exhibit enhanced osc as noted by the highly activated total and reversible oxygen adsorption and co conversion that occurs under isothermal oscillating condition . fig2 shows osc isothermal oscillating test 200 for fresh samples of cu — mn spinel of example # 2 as osm at 575 ° c ., which may include samples of cu 0 . 75 mn 2 . 25 o 4 with zro 2 — nb 2 o 5 support oxide . the samples may be prepared as per of example # 2 to determine co and o2 delay time at temperature of about 575 ° c ., according to an embodiment . in fig2 , curve 202 ( double - dot dashed line ) shows the result of flowing 4 , 000 ppm o 2 through an empty test reactor which may be used for osc isothermal oscillating test 200 ; curve 204 ( dashed line ) depicts the result of flowing 8 , 000 ppm co through the empty test reactor ; curve 206 ( single - dot dashed lines ) shows the result of flowing 4 , 000 ppm o 2 through the test reactor including the disclosed osm ; and curve 208 ( solid line graph ) depicts the result of flowing 8 , 000 ppm co through the test reactor including the disclosed osm . as may be seen in fig2 the o 2 signal in presence of the disclosed cu — mn spinel as osm , as shown in curve 206 , does not reach the o 2 signal of empty reactor shown in curve 202 . this result indicates the storage of a large amount of o 2 in the disclosed osm samples . the measured o 2 delay time , which is the time required to reach to an o 2 concentration of 2 , 000 ppm ( 50 % of feed signal ) in presence of the osm samples , is about 52 . 35 seconds . the o 2 delay time measured from osc isothermal oscillating test 200 indicates that the disclosed osm samples have a significant osc property . similar result may be observed for co . as may be seen , the co signal in presence of disclosed osm showed in curve 208 reach the co signal of empty reactor shown in curve 204 . this result indicates the consumption of a significant amount of co by the disclosed osm samples and desorption of stored o 2 for the conversion of co to co 2 . the measured co delay time , which is the time required to reach to a co concentration of 4000 ppm in the presence of osm samples is about 50 . 46 seconds . the co delay time measured from osc isothermal oscillating test 100 shows that the disclosed osm samples have a significant osc property . based on results of co and o 2 delay time , the behavior of fresh osm samples of example # 2 substantially free from rare metals with spinel composition of cu 0 . 75 mn 2 . 25 o 4 , may outperform the osm samples of example # 1 with spinel composition of cu 0 . 5 mn 2 . 5 o 4 . the measured o 2 delay time and co delay times may be an indication that the disclosed osm , may exhibit enhanced osc properties as noted in the highly activated total and reversible oxygen adsorption , and co conversion that occurs under isothermal oscillating condition . higher air / fuel ratio may provide high oxygen storage capacities , increasing the osc efficiency , by supplying required oxygen to rich exhaust and taking up oxygen from lean exhaust , thus buffering the catalyst system against fluctuating supply of oxygen , optimizing the osc . fig3 depicts a graph of osc carbon balance 300 which may be obtained from fresh samples of cu — mn spinel as osm in example # 2 for isothermal osc test at temperature of about 575 ° c ., employing cu 0 . 75 mn 2 . 25 o 4 composition with zro 2 — nb 2 o 5 support oxide . the osc carbon balance 300 may illustrate what occurs during flowing of co on the osm samples and desorption of stored o 2 for the conversion of co to co 2 . as may be seen in fig3 , curve 302 ( dot lines ) shows the concentration of carbon element in the empty test reactor during flowing of the co feed and curve 306 ( solid line graph ) shows the concentration of carbon element in the osm sample in the test reactor during flowing of the co feed . additionally , curve 304 ( dashed line ) depicts the concentration of co passing through fresh sample of the disclosed osm in reactor and curve 308 ( double dot dashed line ) shows the concentration co 2 formed in the reactor including fresh sample of the disclosed osm in reactor . in fig3 may be observed the formation of co 2 ( curve 308 ) indicates oxidation of co and desorption of stored o 2 during flowing of the co feed . the o 2 required for formation of co 2 is supplied by the o 2 already stored in the disclosed osm sample . the storage of o 2 under lean condition , when the o 2 feed is flowing , and releasing of o 2 under rich condition , when the co feed is flowing , confirm the osc property of disclosed osm sample . the osc of carbon balance shows consumption of co and formation of co 2 in the absence of o 2 because the o 2 required for reaction is provided by stored oxygen in material . the resulting osc properties obtained from fresh samples of the disclosed osm , are indicative of an optimized osc property of disclosed osm sample . according to principles in the present disclosure , the isothermal oscillating osc test for o 2 and co delay time determination which has been done for fresh disclosed osm compare to o 2 and co delay time determination of disclosed osm after aging at different temperatures may illustrate the thermal stability disclosed osm free of rare earth metals . the chemical composition to achieve optimal osc properties and thermal stability , employing cu — mn spinel with niobium - zirconia support oxide as osm , may be determined by comparing variations of cu — mn ratio “ x ” on cu x mn 3 - x o 4 spinel formulation at different temperatures , including but not limited to fresh , aging at 900 ° c ., and aging at about 1000 ° c . fig4 illustrates test results o2 delay time 400 for variation of o 2 delay time for disclosed osm samples without rare metals prepared per example # 1 to example # 3 with different spinel compositions , to perform isothermal oscillating osc test at temperature of about 575 ° c . aged samples have been prepared by hydrothermal aging with 10 % steam at about 900 ° c . for about 4 hours , and by hydrothermal aging with 10 % steam at about 1000 ° c . for about 4 hours . in fig4 , each of the data points represents variations of “ x ” in cu x mn 3 - x o 4 spinel formulation employing stoichiometric and non - stoichiometric spinel deposited on nb 2 o 5 — zro 2 support oxide without rare metals . fresh and hydrothermally aged samples may be employed to measure oxygen delay time in seconds according to temperature , including but not limited to fresh , and hydrothermal aging at 900 ° c ., and aging at 1000 ° c ., identified with data points as follows : for spinel composition of x = 1 . 0 data point 402 ( dot and dash lines ), for x = 0 . 75 data point 404 ( dash lines ), and for x = 0 . 5 data point 406 ( solid lines ). each of the data points represents the measured o 2 delay time in seconds based on the isothermal osc test performed at 575 ° c . for fresh and thermally aged samples at about 900 ° c . and about 1000 ° c ., to compare osm properties of the disclosed cu x mn 3 - x o 4 spinel formulation employing variations of spinel composition , as follows : the osc test results for samples of cu — mn spinel prepared per example # 1 with x = 0 . 5 ( non - stoichiometric structure of spinel ), for fresh samples shows an oxygen delay time of about 45 . 67 seconds , and for hydrothermally aged samples at about 900 ° c . and about 1000 ° c . are about 40 . 95 seconds and about 16 . 98 seconds respectively . comparison of test results of fresh and aged samples at 900 ° c . showing high osc property and thermal stability of this sample , even for aged samples at 1000 ° c . with 16 . 98 seconds shows an acceptable level of osc , which shows disclosed osm has great stability . the osc test results for samples of cu — mn spinel prepared per example # 2 , for fresh samples with x = 0 . 75 ( non - stoichiometric structure of spinel ), shows the resulting oxygen delay time of about 52 . 35 seconds , for hydrothermally aged samples at about 900 ° c . and about 1000 ° c . is about 37 . 81 seconds and about 16 . 98 seconds respectively . comparison of test results for fresh samples with x = 0 . 75 , shows significant increase of oxygen delay time and thermal stability . for aged samples at about 900 ° c . may be observed a slight reduction of oxygen delay time , and for aged samples at 1000 ° c . shows exactly the same level of thermal stability shown as samples with x = 0 . 5 . test results for samples of cu — mn spinel prepared per example # 3 with x = 1 . 0 ( stoichiometric structure of spinel ), for fresh samples shows an optimized oxygen delay time of about 62 . 99 seconds , for aged samples at about 900 ° c . and about 1000 ° c . are about 45 . 54 seconds and about 11 . 18 seconds respectively . test comparison of variations of cu — mn spinel ratio for fresh and aged samples at 900 ° c . with x = 1 . 0 exhibit significant high osc properties and substantial increase of oxygen delay time of about 62 . 99 seconds for fresh sample compare to spinel composition with x = 0 . 5 and x = 0 . 75 . however , hydrothermal aged samples at about 1000 ° c . with cu — mn ratio closer to x = 1 . 0 shows lower oxygen storage capacity , and therefore lower stability . the resulting optimized oxygen delay time properties obtained from fresh samples of disclosed osm without rare metals , may be indicative of dependency of osc properties and thermal stability of cu x mn 3 - x o 4 to the spinel structure and composition , providing an osm without rare metals , which may include optimum composition of cu — mn spinel for optimized osc and thermal stability . fig5 illustrates test results co delay time 500 for variation of co delay time for disclosed osm samples without rare metals prepared per example # 1 to example # 3 with different spinel compositions , performing an isothermal oscillating osc test at temperature of about 575 ° c . aged samples have been prepared by hydrothermal aging with 10 % steam at about 900 ° c . for about 4 hours , and by hydrothermal aging with 10 % steam at about 1000 ° c . for about 4 hours . in fig5 , each of the data points represents variations of cu and mn ratios “ x ” of cu x mn 3 - x o 4 spinel formulation without rare metals employing stoichiometric and non - stoichiometric spinel deposited on nb 2 o 5 — zro 2 support oxide . fresh and aged samples may be employed to measure the co delay time in seconds according to temperature , including but not limited to fresh , and hydrothermally aged samples at 900 ° c ., and at 1000 ° c . temperature . the data points are identify , as follows : for x = 1 . 0 data point 502 ( dot and dash lines ), for x = 0 . 75 data point 504 ( dash lines ), and for molar ratio x = 0 . 5 data point 506 ( solid lines ). each of the data points represents the measured co delay time in seconds based on the osc test performed at 575 ° c . for fresh and hydrothermally aged samples at about 900 ° c . and about 1000 ° c ., to compare osm properties of the disclosed cu x mn 3 - x o 4 spinel formulation employing variations of molar ratio “ x ”, as follows : the osc test results for samples of cu — mn spinel prepared per example # 1 with x = 0 . 5 ( non - stoichiometric spinel ), for fresh samples shows co delay time of about 44 . 55 seconds , and for hydrothermally aged samples at about 900 ° c . and about 1000 ° c . are about 42 . 45 seconds and about 20 . 73 seconds respectively . comparison of test results of fresh and aged samples at 900 ° c . showing high osc property and thermal stability of this sample , even for aged samples at 1000 ° c . the osc test results for samples of cu — mn spinel prepared per example # 2 with x = 0 . 75 ( non - stoichiometric spinel ), for fresh samples shows co delay time of about 50 . 46 seconds , and for hydrothermally aged samples at about 900 ° c . and about 1000 ° c . is about 40 . 4 seconds and about 21 . 43 seconds respectively . comparison of test results for fresh samples with x = 0 . 75 , shows increase of co delay time and thermal stability . for aged samples at about 1000 ° c . may be observed improvement in level of thermal stability compare to spinel with composition ratio of x = 0 . 5 . the osc test results for samples of cu — mn spinel prepared per example # 3 with molar ratio x = 1 . 0 ( stoichiometric spinel ), for fresh samples shows an optimized co delay time of about 64 . 45 seconds , and for hydrothermally aged samples at about 900 ° c . and about 1000 ° c . is about 51 . 05 seconds and about 15 . 06 seconds respectively . test comparison of variations of cu — mn spinel molar ratio , may demonstrate that fresh and aged samples at 900 ° c . with molar ratio x = 1 . 0 exhibit a significant high osc properties , thermal stability and substantial increase of co delay time of about 64 . 45 seconds and about 51 . 05 seconds respectively . however , aged samples at about 1000 ° c . with 15 . 6 seconds shows lower level of thermal stability compare to non - stoichiometric spinel with x = 0 . 5 and 0 . 75 . based on results of osc isothermal oscillating test performed on fresh and hydrothermally aged samples , the disclosed osm without rare metals with variations of cu and mn compositional ratio “ x ” of cu x mn 3 - x o 4 spinel formulation employing stoichiometric and non - stoichiometric spinel deposited on nb 2 o 5 — zro 2 support oxide , may be selected for a plurality of twc applications . fresh samples with stoichiometric spinel structure ( x = 1 . 0 ) exhibit the best performance and optimal osc properties , however , non - stoichiometric spinel structure ( x = 0 . 75 ) may also show optimal stability of osc property . therefore , cu 0 . 75 mn 2 . 25 o 4 spinel formulation may be selected as substitutes for commercial pgm catalyst with osm , given their improved thermal stability and osc properties . the disclosed osm may include a chemical composition substantially free from rare metals , presenting a plurality of advantages over osm traditionally used in catalyst systems , including but not limited to optimum oxygen storage capacity and thermal stability . the osm efficiency may provide solutions for enhanced performance of twc catalyst systems , employing cu — mn spinel as osm without rare metals , and variations of cu — mn molar ratios , with niobium - zirconia support oxide for osm applications , while various aspects and embodiments have been disclosed , other aspects and embodiments are contemplated . the various aspects and embodiments disclosed are for purposes of illustration and are not intended to be limiting , with the true scope and spirit being indicated by the following claims .