مجله بلور شناسی و کانی شناسی ایران
سال هفتم شماره 2 (پیاپی 15، پاییز و زمستان 1378)

The YBa2Cul07_6 (YBCO) superconductor ceramic has low critil..lil current density (Jc) because or weak linb between its grains. There have been a lot or effons to increase Jl. One or Ihe methods to increase Jc is to dope YBCO with other materials such as silver (Ag). In th is paper. the effect of adding silver to YBCO with the weight ratio of 0% 10%,15%. 20% and 30% on its mil:rostrul:lure have been investigated. The X-ray diffraction (XRO) ilnd scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) dj il gra Ul~ of ~ilmpb hilvc been obtained and studied. The study of XRD patterns shows 1ha1 Ag i~ l1 ppCilrs l iS a scparalc ph use in the sa mplc..c; ,.lOti the: position Illchr('39') YBeQ peaks do nut considerable l:hangcs. The study or SEM of samples rcveal~ that the Ag ildtkd to YBea docs not prese nt in its micros tructure and doc~ nnt t.;hangt.: the lattice constants of YBeO by l:()n~lderllbk amount, and also thl: Ag grains remain among YBCO grains ami providc the better intcrgnmular contact. The pi..chr('39')rr.:l!nt<tl!~ 01 chr('39')iilchr('39')CI Ichr('39')m optomll"mg the phy.;;(ill pfllpCr1It.:~ 01 YBeQ ~upcn;()nducturcs i~ almost 20.

Single crystals of binary semiconducto r CdSe were grown by subJimalion and conde nsation techniques wing ca rrier argon gas. Powder X-ray diffraction as well as Transmission e lectron microscopy o f powde red crystals confiml Ihe cryslal st ructure to be hexagonal with :a = 4.299 A, c = 7.010 A and space grope P6,MC

The Tidtir CObHl1 deposit is Im.:alell IX km northwesl 01 Ihe I()wn ul Eqliu, in Ihe S:tlwndaj - Sirjan zonc. Cobalt mincralil.ation occur:-. 111 a Ic horizon)chr('39') concordant Wi lh, and within Ihe :-.cdmlcnlary detrital :-.equem.:cs of limeslom:, sa nd)chr('39')lOnc and marl of upper jurassk (M,dm) age. The main minerals arc magnclile and changing gradually 10 hemalite anu then to limonite and g()clh ile. Co, Ni, Mn, Ti, A:-., bearing minerals also tlI..:cur. These minerals represents an oxidized environment, hu whether coha lt bearing pha~es, (Ire part or the ox idized zone or helong 10 an independent sou rce underneath, is the subject of Ihis study. Association of cobalt wilh Iron, man g~ n Ci>e and day mmcr .. h (),ta,cngcr components) .lotrongly .loUpport thc hypOthc..i 01 ad:-.urbtioll. 11,,; ~ h:-.e lltc of ullramafic oUlcrops. the Slratiform nature of mineralized horizons, the Inw Ph and Zn content s, Ihe absence of indir..:ator minerals of reduced far..:ies, rejcr..:1 the known models of caha lt mineralization (skarn, laterilit, hydrothermal. m<lgmatic and stratiform) for Tidar deposit The weathered m3fie or ultml1afic plulon is probahly the primary source of cahall; The free Cohalt released from thb pluton b transp0 rl cd to the upper Jurassic :-.edimcnt al)chr('39') basin, or had been moved as a CObill! hearing phase to the depos ition si le, where il was weathered and Co was releases. And finall y, the free Cobalt ions ei ther were adsorbed on certain mineral grain s. or INfchr('39') lI~r()~il (chr('39') d ;1~ amrlrphnllS eompollo(h fillin!! the ;,<vOIil;;blc open SPU(;CS,

The rcnccted beam intensity as a lunctlon of dcclron energy ( lIE curve) is studied for an ideal (001) Ni surface by low energy electron diffraction (LEED). Double layer method, rcnormalized forward scattering (RFS) and quasi-dynamic method arc used for lIE curves calculation. The role of structural and nonstructural parameters of Ni on lIE curves is examined. The crfect or the optical potcnti .. , und numbcl o f scnltcrcd bcums on these curve:! arc also studied.

The adsorption of nit ric oxide on a Cu(1l1) surface has been studi ed using X-ray photoelectron (XPS) and high resolution e lectron energy loss spectroscopies (HREEL) in the tcmpenllurc range 80-410 K. Nitricoxide had no interacation with surface at room tempe rature, while it was adsorbed molecularly on un an nealed Cu surface and then dissociated to ni trogen and oxygen atoms. Exposure of surface to NO at 80K showed mo lecular adsorpt ion of NO and N20. The exposure dependent HREEL spectra of NO at the clean Cu su rface at 80K and for subsequent warming up to room temperature showed loss peaks at 344 em-I, 680 em-I, 1525 em-I, 1830 em-I, and 2140 em-I. The vibrational mode at 1830 cm-l was ass igned to N-O stretch of NO handed in a lOp position, the 1525 cm-l loss peak was attributed to the N-O stretch of NO honded in two fold bridge sites, the loss peak at 680 cm-l was assigned to a bending mode of NO(adS) the loss peak at 2140 em-I was due to (N-N) stre tChing mode of N20 formed. The intense feature at 344 em-I was identified as the Cu-NO stre tching mode_

Ccrumic refers to all fircd products incl uding pou ery, hrick. and tile that is primarily composed of clay with different iJlllo unts of o ther materia ls thaI have a source from soil and when they lired .produced a hard material. Firing the clay body to the hanJness of ceramic hody is the next critical stage in manufm:turing. To de termine the firing te mperatu re. four lired (450, 600. 850. 1000°C) togc ther with unfin..:d day samples were studied, usmg XR 0 and STA methods. and then an unidentified tiring temperature sample was examined. Format ion of new mi ne rals in the temperature... m("ntioned above and the stage o f l:arhonah::s e hmin<ltion can he (h;:termined with X RD. but to get a h~th,;r n,;:»u lt, :-opcl:Lally for tho:»e samples which fired tl:lllpL:ratur.! is nearly oOt/°C. it is necc:»s.lry 10 usc STA melhod