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OBJECTIVE: Brain structural changes in schizoaffective disorder, and how far they resemble those seen in schizophrenia and bipolar disorder, have only been studied to a limited extent. METHOD: Forty-five patients meeting DSM-IV and RDC criteria for schizoaffective disorder, groups of patients with 45 matched schizophrenia and bipolar disorder, and 45 matched healthy controls were examined using voxel-based morphometry (VBM). RESULTS: Analyses comparing each patient group with the healthy control subjects found that the patients with schizoaffective disorder and the patients with schizophrenia showed widespread and overlapping areas of significant volume reduction, but the patients with bipolar disorder did not. A subsequent analysis compared the combined group of patients with the controls followed by extraction of clusters. In regions where the patients differed significantly from the controls, no significant differences in mean volume between patients with schizoaffective disorder and patients with schizophrenia in any of five regions of volume reduction were found, but mean volumes in the patients with bipolar disorder were significantly smaller in three of five. CONCLUSION: The findings provide evidence that, in terms of structural gray matter brain abnormality, schizoaffective disorder resembles schizophrenia more than bipolar disorder.

High thermoelectric performances have been reached in Ca3Co4O9 ceramic material through a modified solid state route. Samples were prepared using the classical solid state synthesis method with the addition of different K2CO3 amounts (0, 5, and 10 wt.%). It provides a very flexible, economic and easy processing route which allows microstructural control and improves the sintering procedure. K2CO3, with ∼898ºC melting point produces a liquid phase during sintering procedure (at 900ºC), which is vanished during the process. Electrical resistivity was decreased by enhanced grains connectivity and sizes, while a significant increase in Seebeck coefficient at high temperatures has been produced. The best PF values at 800°C have been obtained in 5 wt.% K2CO3 samples (0.43 mW/K2m), which are much higher than the obtained in bulk sintered materials, and around the best measured in high density ones.

Bi2Sr2Ca1.95Na0.05Cu2Oy + x wt.% Ag materials with x=0, 1, 3, and 5, were prepared by a sol-gel via nitrates method followed by a texturing process by the laser floating zone technique described in detail elsewhere. As it is well known, Na allows raising magnetic properties when it is added in the adequate proportions. Moreover, metallic Ag additions have been shown very advantageous from the point of view of the mechanical and electrical properties. This effect is due to the improvement of the grain boundaries reinforcing, at the same time, the bulk material as Ag is found filling the holes between superconducting grains. As a consequence, the effect of simultaneous addition of the optimum Na amount with different metallic Ag contents will be studied in this work. It has been found that microstructure is directly affected by the Ag amount, and these modifications in microstructure are reflected in changes in the electrical (JC and TC), and mechanical properties (by three point bending).

Time decay of magnetization, known as magnetic relaxation, is crucial for both fundamental and applied point of view in bulk high temperature superconductors (HTS) by setting the limits to the HTS devices stability. Melt-processed BiSrCaCuGaO rods (Bi-2212, x=0, 0.1) were used to study the effect of both grain alignment and substitution on the samples critical current density, relaxation and pinning behavior. The magnetic field has been applied both perpendicular and parallel to the rods growth axis to determine the effect of grain alignment. It has been found that Ga substitution reduces grains orientation and sizes leading to lower magnetic properties. The peaks of the curves, which indicate the temperature dependence of the samples magnetic relaxation rate (S), have been observed in the 7-35 K temperature range. Characteristic pinning energy (U/k) of samples was determined using the formalism developed by Maley. The change of pinning energy as a function of magnetization has been found to be exponential between 3 and 60 K, which is in agreement with the collective creep theory.

Bi2Ca2Co1.7Ox thermoelectric ceramics with small Ag additions (0, 1, 2, 3, 4, and 5 wt.%) have been successfully grown from the melt, using the laser floating zone method and subsequently annealed at 800 °C for 24 h. The microstructure has shown a reduction of the amount of secondary phases for Ag contents up to 4 wt.%. This microstructural evolution leads to a decrease of the electrical resistivity values until an Ag content of 4 wt.%, whereas Seebeck coefficient has been maintained unchanged. This is in agreement with the presence of metallic Ag in all samples, confirmed not only by Energy Dispersive Spectrometry but also by X-ray photoelectron and Auger spectroscopy. These electrical properties lead to maximum power factor values of about 0.30 mW/K2.m at 650 °C for the 4 wt.% Ag containing samples, which is among the best results obtained for this type of materials.

A flexible, adaptable, economical and easily scalable processing route, allowing microstructural control, is presented. It involves classical solid state sintering method and addition of liquid promoting compound. Controlled porosity and high thermoelectric performance have been attained in CaCoO by KCO additions, drastically improving the sintering procedure. KCO behaves as transient liquid phase, providing microstructural benefits, vanishing during sintering. Electrical resistivity was improved by enhanced grains connectivity and growth. Significant increase in Seebeck coefficient at high temperatures has been produced while lattice thermal conductivity was unaffected. The best ZT value, estimated at 800°C, assuming the thermal conductivity value at 140°C, is 0.35 for 5wt.% KCO samples. These values are significantly higher than that obtained in highly-dense textured materials at the same temperature. The results suggest that this approach is very effective for preparing highly-performing CaCoO-based thermoelectric materials with relatively high porosity to control thermal conductivity.

In this paper, the physical and superconducting properties of BiSrCaNaCuO with x=0.0, 0.05, 0.075, 0.1, and 0.20 textured superconducting fiber rods prepared by a laser floating zone (LFZ) technique were studied. The effects of Na substitution for Ca have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transport measurements, dc-magnetization, magnetic hysteresis and magnetic critical current density. The powder XRD patterns of samples have indicated that Bi-2212 phase is the major one, independently of Na content. The best critical temperature, T, has been found as 93.3 K from M-T data for the sample with 0.075 Na substitution. The maximum magnetic J value has been calculated as 1.35×10 A/cm at 10 K for the 0.10 Na sample. The maximum transport critical current density has directly been measured as 1.3×10 A/cm at 77 K for the 0.05Na sample.

Bi2-xPbxBa2Co2Oy (x=0.0, 0.2, 0.4, and 0.6) misfit compounds were grown by the laser floating zone technique. Microstructural analysis has shown the formation of thermoelectric grains together with high amount of secondary phases. Thermoelectric grains orientation is increased until 0.4Pb, while further substitution drastically destroys the preferential grain orientation. Electrical resistivity is very low compared with the values obtained in sintered materials, spectacularly increasing power factor. Moreover, the performance of these materials was further improved subjecting the as-grown samples to a postannealing step due to the rise of thermoelectric phase content. These microstructural modifications led to a high decrease of electrical resistivity, improving power factor in around a factor two at room temperature, compared with the as-grown samples. Moreover, the low thermal conductivity of the textured annealed samples leads to a maximum estimated ZT value of 0.53 for the 0.2 Pb-doped samples, much higher than the reported in literature.

BiPbBaCoO thermoelectric ceramics with small Ag additions (0, 1, 3, and 5 wt%) have been textured using the laser floating zone method. Microstructure has shown a slight decrease on the secondary phases content and a better grain alignment in Ag added samples. These microstructural features are reflected in the thermoelectric properties, which have shown a significant decrease of electrical resistivity, when the Ag content is raised. In spite of a corresponding decrease of Seebeck coefficient, all the Ag-containing samples possess higher Power Factor values than the BiPbBaCoO ones. Moreover, the maximum Power Factor values (about 0.36 mW/K.m at 650 °C) have been measured in BiPbBaCoO+3 wt% Ag samples, which are the best results reported in this family of materials.

Bi2Sr2Co1.8Ox bulk polycrystalline ceramics were prepared by conventional sintering of powders, obtained by polymer solution method and by directional growth using the laser floating zone technique. Microstructural analysis showed randomly oriented grains in the classical sintered materials, while in the laser-textured samples well oriented crystals with the c-axis nearly perpendicular to the growth direction were observed. A significant reduction on electrical resistivity, compared with the sintered materials, was observed due to the decrease on the secondary phases content. As a consequence, a raise on the power factor of about 2 and 5 times, compared with the classically sintered samples, was obtained for the as-grown and annealed laser-textured samples, respectively. The maximum power factor obtained at 650 °C in the annealed laser-textured samples (∼0.20 mW/K2 m) is much higher than the best value obtained in sinter–forged textured materials at the same temperature.

Three different synthesis methods producing nanometric grain sizes, coprecipitation with ammonium carbonate, oxalic acid, and by attrition milling have been studied to produce Ca3Co4O9 ceramics and compared with the classical solid state route. These three processes have produced high reactive precursors and all the organic material and CaCO3·have been decomposed in a single thermal treatment. Coprecipitation leads to pure Ca3Co4O9 phase, while attrition milling and classical solid state produce small amounts of Ca3Co2O6 secondary phase. Power factor values are similar for all three samples, being slightly lower for the ones produced by attrition milling. These values are much higher than the obtained in samples prepared by the classical solid state method, used as reference. The maximum power factor values determined at 800 °C (~0.43 mW/K2 m) are slightly higher than the best reported values obtained in textured ones which also show much higher density values.

Bi2Sr2Co1.8Ox ceramics have been synthesized through solid-state reaction methods and directionally grown from the melt by laser floating zone technique. Mechanical and thermoelectric characteristics of this material were determined by three point bending tests and the four probe technique, respectively. The mechanical and thermoelectric properties of Bi2Sr2Co1.8Ox were determined as a function of the environmental conditions, air and water. Flexural strength data show that textured materials possess a high degradation resistance due to the low porosity of the external part of the rods (~65 µm), which avoids water infiltration and, as a consequence, the internal degradation. Moreover, power factor values are maintained practically unchanged for the samples immersed in water for 24 h.

The effect of environmental conditions on the microstructural, mechanical and thermoelectric properties of highly textured Bi2Ca2Co1.7Ox thermoelectric materials was investigated by powder X-ray diffraction, scanning electron microscopy, three point bending test, electrical resistivity, and thermopower measurements. Textured thin rods were directionally grown from the melt through a laser floating zone melting technique. The mechanical and thermoelectric properties of Bi2Ca2Co1.7Ox were determined as a function of two different environmental conditions, air and water. Flexural strength data showed that these oxide materials possess an unsuspected degradation resistance. These good results have been related to the presence of a very thin (~250 µm) low porosity region and relatively small grain sizes, which avoids the internal degradation by water infiltration through the porosity. Moreover, thermoelectric performances, evaluated through the power factor are maintained practically unchanged, independently of the environmental conditions.

The efforts of carrying forward superconducting materials to commercialization can be overcome by materials with high performance potentiated by a suitable processing technique. In this work, extreme critical currents up to 241 A @ 77 K were attained by tuning the crystal growth in a directional solidification process. Bulk rods of textured Bi-2212/2.9 wt % Ag were obtained by changing the conventional laser floating zone technique through the application of a d.c. electrical current during the crystallization process. Using an optimized composition, the electrically assisted laser floating zone (EALFZ) allowed obtaining 5800 A/cm2 in rods exhibiting only 2.3 mm in diameter, the highest value reported so far for bulk samples. This behavior is a consequence of the texture enhancement and radial phase distribution, exceeding a 2-fold increase in Jc compared with samples grown without electrical current. Morphological and structural observations are discussed and correlated with the results from the electrical characterization. Applications on extremely efficient electrical current leads working at temperatures below 77 K using the above-described materials grown by EALFZ are anticipated.

Ca3Co4O9 + x wt.% Ag (x = 0, 1, 3, 5, and 10) polycrystalline thermoelectric ceramics have been prepared by a sol–gel route via nitrates followed by high temperature treatment before sintering. Out-of-plane XRD data have shown that major phase is the Ca3Co4O9 one, accompanied by metallic Ag. SEM observations have agreed with the XRD data. Apparent density measurements have revealed that all samples possess densities ranging between 80% and 90% when Ag content is raised. Mechanical properties have shown a drastic increase of bending stress when Ag is added to the samples. Electrical resistivity decreases with the Ag content, compared with the pure ones, while Seebeck coefficient slightly decreases. Maximum power factor values around 0.43 mW/K2 m at 800 °C have been achieved for the 10 wt.% Ag samples which is much higher than the measured in the pure Ca3Co4O9 samples.

Ca3Co4-xMnxOy polycrystalline thermoelectric ceramics with small amounts of Mn have been prepared by the classical solid state method. X-ray diffraction data have shown that Ca3Co4O9 is the major phase, with small amounts of the Ca3Co2O6 one. Moreover, they show that the Mn has been incorporated into these two phases. Electrical resistivity decreases, compared with the values for undoped samples, with Mn content until a minimum for the 0·03 doped ones, increasing for higher Mn substitution. Seebeck coefficient does not change in all the measured temperature range, independently of Mn content. The improvement in electrical resistivity leads ∼30% higher power factor values for the 0·03 Mn doped samples than that obtained in the undoped ones. The maximum power factor at 800°C, ∼0·28 mW K-2 m-1, is close to that obtained in much higher density samples, clearly indicating the good thermoelectric properties of these samples.

[EN]: Ca3Co4-xNixO9 (x=0.01, 0.03, and 0.05) polycrystalline thermoelectric ceramics have been prepared by the classical solid state method. As a result of the Ni addition an increase in porosity has been detected. Moreover, the presence of Ni has been related with the increase of Ca2Co3O6 secondary phase and the appearance of a new NiO-CoO solid solution. However, for the 0.01-Ni doped samples an improvement in the thermoelectric performances has been measured. This effect has been related with a decrease in the resistivity values and an increase in the Seebeck coefficient. The raise in the power factor for the 0.01-Ni doped samples, compared with the undoped ones, is between 10 and 25% at 50 and 800 ºC respectively. Moreover, the maximum power at 800 ºC, around 0.25 mW/K2.m, is significantly higher than the best results obtained in Ni doped samples reported previously in the literature., [ES]: Se han preparado muestras policristalinas de Ca3Co4-xNixO9 (x = 0,01, 0,03 y 0,05) mediante reacción en estado sólido. Se ha detectado un incremento de la porosidad en las muestras dopadas con Ni. La adición de Ni también ha provocado el aumento de la fase secundaria Ca2Co3O6, así como la aparición de una nueva fase consistente en una solución sólida de NiO-CoO. A pesar de ello se ha detectado una mejora de las prestaciones termoeléctricas en las muestras con un 0,01 de Ni. Esta mejora ha sido provocada por una disminución de la resistividad eléctrica y un aumento del coeficiente Seebeck.

Ca3−xBaxCo4O9 bulk polycrystalline thermoelectric ceramics with x = 0.00, 0.01, 0.03 and 0.05 have been prepared through a classical solid state method. Microstructural characterizations of sintered samples have shown that Ba has been incorporated into the Ca3Co4O9 and/or Ca3Co2O6 structures and that no Ba-based secondary phases have been produced. The apparent density values increase when the amount of barium is raised with respect to the undoped samples, reaching a maximum value of around 77 % of the Ca3Co4O9 theoretical density, for samples with the highest amount of barium. Electrical resistivity of doped samples decreases in the whole measured temperature range with respect to the undoped ones, while Seebeck coefficient remains practically unchanged. In conclusion, the improvement in resistivity leads to power factor values which are higher than the ones measured in undoped samples, fact which makes this bulk polycrystalline compound a promising candidate for high-temperature power generation applications in oxidative environments.

Bi-2212 samples prepared by a solid-state reaction technique have been grown from the melt using the laser floating zone method. After annealing the as-grown bars, the samples showed a good grain alignment and a high transport critical current density. Secondary annealing processes were performed on the annealed samples with the aim of producing Bi-2212 phase controlled decomposition. Hence, the Bi-2201 phase and the secondary phases, which act as effective pinning centers, were obtained with the secondary annealing process. After these thermal treatments, the transport critical current densities of samples significantly increased, when compared to the annealed ones. The maximum critical current density was achieved when the samples were subjected to secondary annealing at 680°C for 168 h with an improvement of ~80%, compared to the annealed ones. Moreover, it was found that magnetization of the secondarily annealed samples was also increased. The magnetic critical current densities in these secondary annealed samples were about 3 times higher than the values obtained for the annealed ones. These results clearly indicate that the secondary annealing processes lead to the formation of effective pinning centers in the bulk material.

In the present work, the influence of Yb substitution for Bi on the structural, electrical and magnetic properties of textured Bi-2212 ceramics has been investigated. X-ray diffraction studies indicated that the major peaks correspond to the Bi-2212 phase. The SEM images clearly show that there is an increase in the number of secondary phases with raising Yb content while all samples maintain similar grain morphology. Magnetic analysis of all samples has been done by magnetic hysteresis measurements, indicating that an enhancement in the M-H loops is obtained by a low Yb doping. The critical current density of samples was calculated from the M-H curves by using Bean’s critical state model, indicating that sample with 0.05 Yb substitution possesses the highest Jc values.

Ca3-xNaxCo4O9 polycrystalline thermoelectric ceramics with small amounts of Na (x=0, 0.01, 0.03, 0.05, 0.07, and 0.10) have been prepared using the classical solid state method. Microstructural characterization has shown that Na has been incorporated into the Ca3Co4O9 phase and that no Na-based secondary phases have been produced. It has also been found that Na addition promotes grain growth and favours sintering due to the formation of a small amount of liquid phase. Electrical resistivity decreases when Na content increases until 0.07Na addition while Seebeck coefficient is maintained practically unchanged. The improvement in electrical resistivity leads to higher power factor values than the usually obtained in samples prepared by more complex and expensive techniques.