Developments in Ceramic Materials Research

More documents

Recommendations

Info

110 José M. Rojo, José L. Mesa and Teófilo Rojo However, considering the simulations report by other authors [3,41,42] the observed ESR spectra may suggest the presence of three different sites for the chromium ions in the Cr(PO3)3 phase. One of them with |D|> hν and the other two with |D|< hν. These results are in good agreement with the crystallographic data that show the existence of an octahedron with a larger distortion than that observed for the other two. 5.4. ESR of Fe(PO3)3 The powder X-band ESR spectra of Fe(PO3)3 at different selected temperatures are shown in Figure 8a. Figure 8. (a) Powder X-band ESR spectra at different temperatures and (b) temperature dependence of 1/I of the signal and the linewidth curves for the Fe(PO3) 3 compound.
Synthesis, Spectroscopic and Magnetic Studies… 111 In all cases isotropic signals centered around g= 2 were observed. These signals are characteristic of Fe(III) cations in octahedral environment without large tetragonal distortion. The room temperature spectrum (g= 1.99) fits exactly the characteristic of a Lorentzian curve being the same result obtained for all spectra registered down 10 K. Below 10 K the fits are not considerably good. The temperature dependence of the intensity and linewidth of the signal calculated by simulation of the experimental spectra to Lorentzian curves is displayed in Figure 8a. The g values remain apparently unchanged in all the temperature range studied. The intensity of the signal increases with decreasing temperature, reaches a maximum at about 12 K and after that rapidly decreases [see Figure 8b]. In fact, at 4.2 K no relevant signal could be observed. As can be deduced from the straight line that fits the 1/I vs. T curve at high temperatures the magnetic susceptibility of the compound follows a Curie-Weiss law and no short order effects are detectable above 30 K. As long as the high temperature conditions (kT>> Hz, Hex, Hdip,…) is expected to be satisfied than the line width observed has low temperature dependence. Only a small increase is observed between room temperature and 50 K probably due to the dipolar homogeneous broadening. Furthermore, when temperature is decreased the linewidth increases rapidly reaching a maximum at 8 K. This behavior is characteristic of systems with a threedimensional order and, in this case, it must be of antiferromagnetic nature considering the thermal evolution of the intensity of the signal [43,44]. The apparent temperature independence of the resonance field is also in good agreement with a three-dimensional behavior with quasi-isotropic interactions. In any case, the presence of three different Fe(III) sites and the relatively large linewidth (430-1050 Gauss) imply that the conclusions observed from the powder spectra must be considered with caution. In fact, the observed isotropic signal is the result of the collapse by exchange of those expected for the three different Fe(III). 6.1. Magnetic Properties of Ti(PO3)3 6. MAGNETIC PROPERTIES Variable-temperature magnetic susceptibility measurements, performed on a powder sample of Ti(PO3)3 from 1.8 to 100 K are shown in Figure 9. The χm -1 vs. T line follows a Curie-Weiss law in practically all the temperature range studied. The Curie constant value is Cm= 0.17 cm 3 Kmol -1 , which is notably lower than that expected from the g-values obtained from the ESR spectra. The calculated value of the Curie-Weiss constant is θ= +0.31 K. The χmT product at room temperature is 1.17 μB and remains unchanged until 20 K. At lower temperatures than 20 K a slight increase of the χmT product can be observed. This result suggests the existence of ferromagnetic interactions in the Ti(PO3)3 compound. 6.2. Magnetic Properties of V(PO3)3 The thermal evolution of the molar magnetic susceptibility for the V(PO3)3 compound is shown in Figure 10. The susceptibility follows a Curie-Weiss law between 1.8 and 300 K
Page 3:
DEVELOPMENTS IN CERAMIC MATERIALS R
Page 6 and 7:
Copyright © 2007 by Nova Science P
Page 9 and 10:
PREFACE Ceramics are refractory, in
Page 11 and 12:
Preface ix crystals is discussed. A
Page 13:
Preface xi spectra and the directio
Page 16 and 17:
2 Leslie G. Cecil comprehensive dat
Page 18 and 19:
4 Leslie G. Cecil Ringle et al. (19
Page 20 and 21:
6 Leslie G. Cecil The main architec
Page 22 and 23:
8 Leslie G. Cecil can study “the
Page 24 and 25:
10 Leslie G. Cecil Middleton et al.
Page 26 and 27:
12 Leslie G. Cecil The laser ablate
Page 28 and 29:
14 Leslie G. Cecil There are two ge
Page 30 and 31:
16 Leslie G. Cecil distinct recipes
Page 32 and 33:
18 Leslie G. Cecil second group (Fi
Page 34 and 35:
20 Leslie G. Cecil The Vitzil-Orang
Page 36 and 37:
22 Leslie G. Cecil Table 3. Mahalan
Page 38 and 39:
24 Leslie G. Cecil Ixlú and Ch’i
Page 40 and 41:
26 Leslie G. Cecil structures (D. R
Page 42 and 43:
28 Leslie G. Cecil paste and Macanc
Page 44 and 45:
30 Leslie G. Cecil Bieber, A. M. Jr
Page 46 and 47:
32 Leslie G. Cecil Kepecs, S. M., a
Page 48 and 49:
34 Leslie G. Cecil Schele, L., Grub
Page 50 and 51:
36 Z. C. Li, Z. J. Pei and C. Tread
Page 52 and 53:
Page 54 and 55:
Page 56 and 57:
Page 58 and 59:
Page 60 and 61:
Page 62 and 63:
Page 64 and 65:
Page 66 and 67:
Page 68 and 69:
54 T. T. Basiev, V. A. Demidenko, K
Page 70 and 71:
Page 72 and 73:
Page 74 and 75: 60 T. T. Basiev, V. A. Demidenko, K
Page 76 and 77: 62 I, % 100 80 60 40 20 0 T. T. Bas
Page 82 and 83: 68 Fluorescence, a.u. 1 T. T. Basie
Page 84 and 85: 70 Fluorescence, a.u. 1 0.1 0.01 0.
Page 92 and 93: 78 k, cm -1 20 18 16 14 12 10 8 6 4
Page 96 and 97: 82 Photon counts 300 250 200 150 10
Page 98 and 99: 84 Fluorescence, a.u. I transfer ,
Page 100 and 101: 86 ln(I transfer (t)) -4.2 -4.4 -4.
Page 102 and 103: 88 Fluorescence, a.u. I transfer ,
Page 111 and 112: In: Developments in Ceramic Materia
Page 113 and 114: Synthesis, Spectroscopic and Magnet
Page 115 and 116: a c Synthesis, Spectroscopic and Ma
Page 119 and 120: Transmission Transmission Transmiss
Page 123: Synthesis, Spectroscopic and Magnet
Page 137 and 138: Sm (J/Kmol) Sm (J/Kmol) 15 10 5 Syn
Page 145 and 146: Intensity (a.u.) Intensity (a.u.) 8
Page 155 and 156: In: Developments in Ceramic Materia
Page 157 and 158: The Use of Ceramic Pots in Old Wors
Page 163 and 164: 3.2. Wall-in Positions The Use of C
Page 171 and 172: IACC ( τ ) = t2 ∫ The Use of Cer
Page 175 and 176:
where σ res is the scattering cros
Page 177 and 178:
The Use of Ceramic Pots in Old Wors
Page 179 and 180:
D50 0.8 0.7 0.6 0.5 0.4 0.3 The Use
Page 181 and 182:
Definition (D50) 1 0.95 0.9 0.85 0.
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
In: Developments in Ceramic Materia
Page 189 and 190:
Modeling of Thermal Transport in Ce
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
q x = Modeling of Thermal Transport
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
Page 221 and 222:
Page 223:
Page 226 and 227:
212 R. Ramesh, H. Kara, Ron Stevens
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
220 ε S 33 R. Ramesh, H. Kara, Ron
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
242 Development of Display Technolo
Page 258 and 259:
244 Li Chen technology moved to the
Page 260 and 261:
246 Li Chen The continuing evolutio
Page 262 and 263:
248 Li Chen the back contact cathod
Page 264 and 265:
250 Li Chen Figure 3. Vertical side
Page 266 and 267:
252 Li Chen Figure 6. Molybdenum mi
Page 268 and 269:
254 Li Chen Figure 8(a). I-V curve
Page 270 and 271:
256 Li Chen Figure 9. Life time tes
Page 272 and 273:
258 Figure 11(a). Plasma generated
Page 274 and 275:
260 Li Chen [13] C.A. Spindt, K.R.
Page 276 and 277:
262 S. Ardizzone, C. L. Bianchi, G.
Page 278 and 279:
Page 280 and 281:
Page 282 and 283:
Page 284 and 285:
Page 286 and 287:
Page 288 and 289:
Page 290 and 291:
Page 292 and 293:
Page 295 and 296:
A absorption spectra, 66, 67, 77, 7
Page 297 and 298:
correlation function, 156 corrosion
Page 299 and 300:
group membership, 13, 20, 21, 22, 2
Page 301 and 302:
microstructure(s), x, xi, 73, 74, 2
Page 303 and 304:
efraction index, 61 refractive inde
Page 305 and 306:
time, vii, ix, 1, 3, 7, 8, 11, 26,
show all

Developments in Ceramic Materials Research

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?