مجله بلور شناسی و کانی شناسی ایران
سال سوم شماره 2 (پیاپی 8، پاییز 1374)

Electron microscopes (SEM, TEM) and electron microprobe (EPMA) are useful research equipments that can be used to examine the mineral raw materials and also their industrial products and defi nite ly through the produc ti on process of tr a nsform ing the minerals to industrial products. These are useful equipmen ts, that can provide all the information about weakly crystaline minerals that could not be obtained by-X-rays methods (XRD,XRF), Determination Thermal Analysis (DTA) o r o ptical microscopy. Particle size distribution - shape and crystalline size of mine rals - tex ture and recog nizing non crystalline phases and quantit ative analysis of minerals and tbeir products are just a few things of these equipments vast abilites.

Si ng le c rys t als o f bin a ry semico ndu c to rs CdTc,CdSe. PhTe and PbSe were grown by sublimat ion and condensa tion techniq ues usi ng argon as the carri e r gas. Powder X-ray di ffractomet ry as wel l as La ue mClhod wcre employed fo r the stru ct ura l a na lysis. By usi ng Ha ll techniq ue. the de nsity and polarity of charge car rie rs we re de te rmined in single crysta ls. PbTc and PbSc c rys ta ls were grown as p-type wit h charge densi ty of about l.l x1Q 18 em·3 whereas CdTc and CdSe were grown as intrinsic. Thcrmo * elcctric technique was also uliliscd to dc le rmine the e nergy gap of single and polycrystals of CdTc and CdSc.

To study the effect of microstracturcs,long-time grinding and nonmagnetic phase on magnl;tic properties of barium fe rrite, isotropic samples of ba rium ferrile magnets, BaU.6Fc203. were prepared by ce ra mics and co - precipitation methods. Magnetic measurments indi ca tes a higher demagnetization of the samples prepared by <.:hemical method due to lack of rcmcnant stress and crystallographic imperfect ions in th is case. Also, the inter med iate nonmagnetic phases is less in samples prepared hy chemical method. The optimum si ntering temperature for maximum store of magnet ic e nergy is 925-950°C fo r che mica l and 950- 1000°C for ceramic methods.

Thl.: Ri elwc ld mc thod ofstructurl.: refinement from powder dilTr<:lction patterns is widely used with neutron data and int:reasingly so with x* ray data . [n this p<:lper the Ril.:tveld method has hccn cxplainl.:d. As an ex.ample the t: rystal :-.truclure of LazCu04 at rollm It:mperaturc has been refined using x*ray powder dirfr<:lctiol1 data. The crystal ,lruc lure is llflhorombi c wilh a = 5.154S(4)A . h = 5.411116(1)A . c = 13.1529 (9)A. and space gfllUp em,"chr('39') A sample of La2Cu04 has been oxidized to La2Cu04+0 and its magnetic susceptibily as a function or temperature has heen studied. The new m(ltcrial is supcrconductor with Tc == 30K. Further investigation is in progress to determine the va lue or () and the position of the extra oxygen atOl11s in tht..: cell.

A new complex of cadmium was synthesized by the reaction of cadmium nitrate, potm;sium dichromate, and ethylenediamine. Its crystal structure was dete rmined by X-ray diffractomctry. It is Crystalli:tt.:d in a monoclinic system, with P21 /n(1 4) poinl group and 4 molecules of the complex in the unit ceiL The cryst,d parameters arc:a = 7.4615(7)A. h= 7.1480(2)A. c= 14.~4B5( 10)A /3= 92.(196. V =79IAI(IO)A3 Because of the un usual bridge ligands of et hylenedi(lmine and chromate, the complex has an interesting structure. which is 3-dimensional and polymeric

Samples of BaTi03, PbTi0 3, and Pb (Tix,Zr ].x)0 3 (x=0.4 7) was pre pare d usi ng so lid and liquid phase me th ods. Mi cros tru cture study o r lh ese samples show a h ig h ~ r degree of homogeneity, higher density and reactivity in samples made by solutions phase method as compared to the solid phase technique.

Homoginization temperature of fluorite [luid indus ian indicate that mineralization has mostly take place within the temperature ranging 70 to 1500C . the last ice melting tcmpenttur ranges from 0 1O·2.2°C and shows that salinity varies from 0 to 3.69 wt% equivalent NaC!. Chemical analysis performed on The liquid phases of fluid indusion show that mineralizing fluids were rich in Ca and K. The above results along wilh data obtained by SEM equipped with EDAX spectrophotometery reveals that metal deposit of this mine were probably transported by chloride complexes. Temperature decrease and boiling accurancy were probably the cause of decomposition of chloride complex at the depusitiunal sites.