below , a detailed description will be given of the present invention , with reference to the accompanying drawings . ag powder 99 . 9 % pure was melted in a vacuum and molded into a bar having a diameter of 20 mm . the bar was deformed into a rod having a cross section of 6 × 6 mm 2 by drawing . the rod was annealed at 300 ˜ 400 ° c . for 1 hour in air and rolled into a sheet 0 . 2 mm thick ( 97 % reduction ) in a tape form . after being polished by 10 μm in the thickness direction , the 97 % cold - rolled sheet was measured for orientation distribution function ( hereinafter referred to as “ odf ”). fig1 shows odf diagrams of the ag sheet taken for an euler space of φ 2 = 0 ° ( a ), φ 2 = 30 ° ( b ), and φ 2 = 45 ° ( c ). a cold - rolled ag sheet , polished by about 100 μm , was found to have odf diagrams similar to those of fig1 . the sheet was annealed before observation of the microstructure thereof using an optical microscope ( hereinafter referred to as “ om ”). fig2 shows optical microscope photographs of the longitudinal cross sections of the ag sheets cold - rolled by 97 % and annealed at 300 ( a ) and 850 ° c . ( b ), respectively , for 1 hour in a vacuum . as seen in the images , the size of the grains in fig2 a (& lt ; 10 μm ) is much smaller than that of the grains in fig2 b (& gt ; 50 μm ). an ag sheet annealed first at 300 ° c . for 1 hour and then at 850 ° c . for 1 hour showed an om image similar to that of fig2 b . these observations together suggested that the primary crystallization occurred at 300 ° c . and the secondary crystallization at 850 ° c . moreover , scrutiny of fig2 b reveals that the grain size is smaller in area near the surface of the sheet than in the center area . it was found that these data , although obtained by annealing in a vacuum , are also true of the ag sheet annealed in air . an examination was made of physical properties of the ag sheet which was further annealed at around 850 ° c . as will be described later , a tl - 1223 precursor film is formed on the ag sheet and then annealed at around 850 ° c . in order to transform the precursor to the tl - 1223 phase with a biaxial texture . therefore the ag sheet is annealed at around 850 ° c . using the same method as above . odf diagrams were taken from ag sheets thermally treated as mentioned above . fig3 shows odf diagrams of the ag sheets taken for an euler space of φ 2 = 0 ° ( a ), φ 2 = 30 ° ( b ), and φ 2 = 45 ° ( c ) after they are thermally treated at 300 ° c . for 1 hour and polished by 10 μm in the thickness direction . as seen in fig3 , the ag specimen has two texture components { 023 }& lt ; 032 & gt ; and { 236 }& lt ; 385 & gt ; (≈{ 113 }& lt ; 121 & gt ;), demonstrating that primary recrystallization was completed in this sheet . a specimen polished by 100 μm was found to show odf diagrams similar to fig3 , as well . next , the thermally heated ag sheet was subjected to x - ray diffraction ( hereinafter referred to as “ xrd ”) analysis . fig4 a is an xrd pattern of a sheet heated at 300 ° c . for 1 hour and polished by 10 μm , while fig4 b and 4 c are xrd patterns of sheets heated at 850 ° c . for 1 hour and polished by 10 μm and 100 μm , respectively . in the xrd pattern , as a rule , the peak heights represent the extent to which the lattice planes exist parallel to the sheet surface . in fig4 a , ( 220 ) and ( 113 ) diffraction peaks appear to have almost the same intensity as the ( 111 ) peak . similar results were obtained from the specimen heated at 300 ° c . for 1 hour and polished by 100 μm . as apparent from the data of fig4 b and 4 c , ( 220 ) and ( 113 ) peaks were lower in intensity than was the ( 111 ) peak . in example 1 , as described above , it was demonstrated that the non - elongated ag sheet , which has been subjected to primary recrystallization by thermal treatment at 300 ° c ., experienced the second recrystallization caused by annealing at a temperature as high as 850 ° c . in this example , ag sheets were partially elongated before an annealing process in order to examine the effect of the stress , i . e ., elongation stress , on the secondary recrystallization . the 97 % cold - rolled ag sheet prepared in example 1 was annealed at 300 ° c . for 1 hour , elongated by 0 . 5 % and thermally treated at 850 ° c . for 1 hour . an om image of the ag sheet is shown in fig5 . as seen in the image of fig5 , most grains in the specimen are smaller than 20 μm , and much smaller than those in the specimen of fig2 b , which was heated to 850 ° c . without elongation , indicating that elongation is helpful for suppressing secondary recrystallization of the ag sheet . with reference to fig6 , odf diagrams are shown for an ag sheet which was annealed at 300 ° c . for 1 hour , elongated by 0 . 5 %, heated at 850 ° c . for 1 hour and polished by 10 μm in the thickness direction . the texture , as shown in fig6 , is almost the same as in fig3 . despite the second heat treatment at a temperature as high as 850 ° c ., no secondary recrystallization occurred in the sheet . similar results were obtained from the 97 % cold - rolled ag sheet which was elongated by 1 % and heated at 850 ° c . for 1 hour after annealing at 300 ° c . for 1 hour . fig7 is an xrd diagram of an ag sheet which was annealed at 300 ° c . for 1 hour , elongated by 0 . 5 %, heated at 850 ° c . for 1 hour and polished by 10 μm in the thickness direction , in that order . as seen in the xrd pattern of fig7 , the intensity of the ( 113 ) peak remained high even after annealing at 850 ° c ., indicating that the ( 113 ) [ 121 ] texture was intensified in the elongated ag sheet although it was annealed at 850 ° c . with reference to fig8 , an om photograph of the 97 % cold - rolled ag sheet prepared in example 1 is taken after a series of processes of annealing at 300 ° c . for 1 hour , elongation by 3 %, and thermal treatment at 850 ° c . for 1 hour . as seen in fig8 , grains are not small , which indicates that elongation by 3 % has no positive influence on the intensification of the ( 113 ) [ 121 ] texture in the ag sheet . an xrd pattern , shown in fig9 , was taken from the ag sheet , which was annealed at 300 ° c . for 1 hour , elongated by 3 %, heated at 850 ° c . for 1 hour and polished by 10 μm in that order . it is apparent from the xrd data of fig9 that the intensity of ( 113 ) peak decreases due to the occurrence of the secondary recrystallization and that the ( 220 ) peak has very strong intensity . this indicated that elongation by 3 % gives no benefit in intensification of the ( 113 ) [ 121 ] texture . in contrast , elongation by 1 % or less , as in example 2 , was found to suppress the occurrence of the secondary recrystallization , resulting in intensifying the ( 113 ) [ 121 ] texture in the ag sheet . the reason that the additional , slight deformation caused the suppression of the secondary recrystallization may be as follows . when dislocations accumulate at grain boundaries due to additional deformation , the movement of the grain boundaries is restricted during annealing even at as high as 850 ° c . fig1 ( a ) is an om photograph taken from an ag sheet which was annealed at 300 ° c . for 1 hour and then elongated by only 0 . 5 %. it is observed that the grain boundaries are not as clear as compared to before the elongation ( fig2 ( b )). it seems reasonable to consider that the accumulated dislocations partly destroy their structure . with reference to fig1 ( b ), an om photograph was taken of an ag sheet which was annealed at 300 ° c . for 1 hour and then elongated by 3 %. grain boundaries are unclear compared to those of fig1 ( a ), reasonably suggesting that the dislocations had accumulated inside grains as well as at grain boundaries . taken together , data obtained in this example indicate that the dislocations are limited to grain boundaries when resulting from small elongation and can affect even the inside of grains when resulting from large elongation , so that textured ag substrates having desired properties can be prepared by controlling the extent of the elongation imposed thereon . although the preferred embodiments of the present invention have been disclosed for ag sheets only , those skilled in the art will appreciate that various modifications , additions and substitutions are possible . for example , an ag sheet may comprise non - magnetic alloy sheets with high mechanical strength , such as ni — w , ni — cr , ni — cu — w , ni — cu — cr , ni — pd — cu or ni — pd — w sheets , wherein the ag sheets are laminated on the top , the lower or both side surfaces of the alloy sheet , in order to compensate for the poor mechanical properties of ag , which should be understood as falling within the scope and spirit of the invention . it is preferable that the { 113 }& lt ; 121 & gt ; textured ag substrate further comprises an ag alloy sheet which is alloyed with a small amount of a metallic element selected from among mg , pd , mn , w , ni , fe , cr , v , ti , zn , ti and combinations thereof for improving mechanical properties of the sheet without hindering the occurrence of the intensified { 113 }& lt ; 121 & gt ; texture . it is also preferable that the { 113 }& lt ; 121 & gt ; textured ag substrate further comprises a composite sheet of ag and nonmagnetic alloy wherein the ag sheet is laminated on an upper , a lower or both side surfaces of an alloy sheet made from a non - magnetic alloy having high mechanical strength . in a modification of this substrate , the composite sheet ranges in total thickness from 0 . 05 to 0 . 2 mm , and thickness of ag from 1 μm to 0 . 1 mm . a tl - 1223 film was prepared on each of two ag substrates separately using an electro - deposition method and a thermal treatment in an atmosphere of tl 2 o vapor . one ag substrate had an intensified ( 113 ) [ 121 ] texture and the other was not intensified in ( 113 ) [ 121 ] texture . no additional elongation was conducted on the ag substrates during the preparation of the tl - 1223 film . fig1 a and 11 b are xrd diagrams of the tl - 1223 films which were prepared on the ag substrates with and without intensified ( 113 ) [ 121 ] texture , respectively . in both the diagrams of fig1 a and 11 b , the xrd peaks are those only from the tl - 1223 phase . the heat treatment condition for the specimen of fig1 b was found to be better than that for the specimen of fig1 a , as demonstrated by the more remarkable ( 001 ) peak of the tl - 1223 phase exhibited by the specimen of fig1 b than that exhibited by the specimen of fig1 a . fig1 a and 12 b are sem photographs of the tl - 1223 films which were prepared on the ag substrates with and without intensifying the ( 113 ) [ 121 ] texture , respectively . fig1 shows the alignment and homogeneity of grains of the tl - 1223 phase inside the films which are polished because of the high possibility that their surfaces are covered with non - superconducting impurity phases . as seen in the sem photographs , the grains of fig1 a are more homogeneous in size than those of fig1 b . in addition , almost all of the grains of fig1 a have surfaces perpendicular to the c - axis of tl - 1223 , while a number of grains of fig1 b are not in such a condition , which indicates that the ( 001 ) plane of the tl - 1223 phase hts film epitaxially grows in the [ 001 ] direction on the ag substrate with ( 113 ) [ 121 ] texture intensified therein . although the formation of the film on the substrate has been disclosed with electrodeposition and thermal treatment in a thallous atmosphere , those skilled in the art will appreciate that various modifications , additions and substitutions are possible . for example , pulsed laser deposition , sputtering deposition , e - beam coevaporation , mocvd ( metallo organic chemical vapor deposition ), metallo organic decomposition , sol - gel , malic acid - route screen printing and spray pyrolysis may be utilized instead of electrodeposition , and should be understood as falling within the scope and spirit of the invention . as described hitherto , the application of slight elongation to a primarily recrystallized ag sheet suppresses the occurrence of secondary recrystallization therein , thereby intensifying the ( 113 ) [ 121 ] texture components and reducing the size of the grains (& lt ; 20 μm ) in the ag sheet . in addition , the ag substrate can be utilized to form thereon a biaxially textured tl - 1223 phase film , thereby affording a hts tl - 1223 coated conductor having a high critical current density , in accordance with the present invention . further , the present invention enjoys the advantage of fabricating hts coated conductors at a low production cost because neither highly pure ag sheets nor buffer layers are needed . moreover , the rolling process for preparing an ag sheet can be conducted in air , and thus the present invention is much simpler than conventional ones . the coated conductors fabricated according to the present invention can find a broad range of applications , including cables , magnets , transformers , motors , fault current limiters , generators , electromagnetically propelled ships , accelerators , magnetic levitation vehicles , superconducting magnetic energy storage systems , magneto hydrodynamic generators , resonators , filters , etc .