Carlos E. Bamberger

Synthesis and characterization of sodium-titanium phosphates, Na4(TiO)(PO4)2, Na(TiO)PO4, and NaTi2(PO4)3

Experimental examination of part of the system Na/sub 2/O-TiO/sub 2/-P/sub 2/O/sub 5/ revealed the existence of two new sodium-titanium phosphates, Na(TiO)(PO)/sub 4/ and Na(TiO)P)/sub 4/. Their synthesis was accomplished by several different reactions and their identity was established by means of Raman spectroscopy and X-ray diffraction. Additionally, novel reactions for the synthesis of NaTi/sub 2/(PO/sub 4/)/sub 3/ have been demonstrated.

Raman Spectroscopy of Potassium Titanates: Their Synthesis, Hydrolytic Reactions, and Thermal Stability

The majority of the potassium titanates described in the literature were synthesized, and their Raman spectra recorded. The identity of the compounds K2TiO3, K2Ti2O5, K2Ti4O9, K2Ti6O13, and K2Ti8O17 was confirmed by x-ray diffraction. Raman spectroscopy was then used to study the hydrolysis, under different conditions, of K2Ti2O5 and of K2Ti4O9. On drying of the hydrolysis products, the following species were found to form: K2(H2O)0.66 Ti8O16(OH)2, K1.33(H2O)0.33Ti4O8.33(OH)0.67, and H2Ti8O17. On ignition at temperatures of 500–600°C these species converted, respectively, to K2Ti8O17, K2Ti6O13, and TiO2(B). Raman spectroscopy was used to establish that (1) K6Ti4O11 consists of a mixture of K2TiO3 and a new compound K4Ti3O8; (2) K2Ti3O7 consists of a mixture of K2Ti2O5 and K2Ti4O9, and (3) K2Ti5O11 consists of a mixture of K2Ti4O9 and K2Ti6O13. The temperature of decomposition and the identity of the products of the thermal decomposition of K2Ti8Ol7, K2Ti4O9, K2Ti2O5, and K4Ti3O8 were determined by Raman spectroscopy. The XRD data of the newly identified compounds are reported.

Raman Spectroscopic Observation of Laser-Induced Oxidation of Transition-Metal Borides, Carbides, and Nitrides

Laser Raman microprobe examination in air of small-particle-sized (powders and whiskers) TiN, TiB2, TiC, WC, ZrN, and NbN revealed the formation of surface oxides, which were induced by laser heating. The rate of oxide formation varied with the particle size of the samples and the laser power density applied. The oxides produced were characterized by their Raman spectra. Thus, the Raman spectra obtained with a microprobe should always be carefully analyzed to ascertain whether oxidation or decomposition of so-called inert materials, especially in powder form, has occurred.

Synthesis and characterization of titanium phosphates, TiP2O7 AND (TiO)2P2O7

Abstract TiP 2 O 7 and (TiO) 2 P 2 O 7 were synthesized using novel reactions. Their Raman spectra were recorded and the X-ray diffraction pattern of (TiO) 2 P 2 O 7 powder was obtained. The thermal stability of both compounds was established by means of Raman spectroscopy.

Aqueous leachability of lanthanide and plutonium titanates

Abstract The leachabilities of titanate and zircono-titanate solid solutions, Ce 2 Ti 2 O 7 , Er 1.78 Ce 0.22 Ti 2 O 7 , Er 1.78 Pu 0.22 Ti 2 O 7 (9.5 wt% Pu) Er 1.78 Ce 0.22 Ti 0.5 Zr 1.5 O 7 , SrCe 2 Ti 4 O 12 , SrPu 2 Ti 4 O 12 (50.7 wt% Pu) and Sr 2 Ce 2 Ti 5 O 16 , have been investigated in WIPP ‘A’ brine, 0.1 M NaCl, and 0.1 M HCl solutions using a modified MCC-3 procedure with a duration of 60 days. The concentrations of plutonium leached by the brine were less than 1 ppm. Where cerium was used as a surrogate for plutonium, its concentration in WIPP brine was below the limit of detection (10 ppm) established for the inductively coupled plasma (ICP) atomic emission spectrometer used. Concentrations of strontium leached by WIPP brine from stable strontium-containing titanate compounds, considered as possible immobilizers of both 90 Sr and actinide elements, were on the order of 30–60 ppm.

Synthesis and characterization of crystalline phosphates of plutonium(III) and plutonium(IV)

Abstract The formation of both PuPO4 and PuP2O7 from reactions of PuO2 with (NH4)2HPO4 or BPO4 was studied by X-ray diffraction and Raman spectroscopy. The oxidation of plutonium(III), in PuPO4, to plutonium(IV), in PuP2O7, by air in the presence of BPO4 and the thermal reduction of PuP2O7 to PuPO4 were demonstrated. In addition plutonium(III) trimetaphosphate Pu(PO3)3 was synthesized and characterized. Attempts to prepare plutonium(IV) orthophosphate, Pu3(PO4)4, by high temperature reactions were unsuccessful; instead, mixtures of PuP2O7 and a new phase identified tentatively as “(PuO)2P2O7” were obtained.

Substitutional solid solutions from heterotypic lanthanide dititanates Ln2−xLn'xTi2O7

Abstract The formation of substitutional solid solutions of dititanates containing two lanthanide ions from heterotypic mixtures, monoclinic and cubic, at temperatures up to 1500 °C was studied by Raman spectroscopy and X-ray diffractometry. All the results were fitted to a stability diagram by means of two parameters: the percentage difference δ in the ionic radii of each lanthanide pair and the unit cell volume V of the resulting crystal. The boundary between cubic phases and the region of restricted miscibility provides information on the solubility of the monoclinic phase in cubic lanthanide dititanates. This can be used to predict the solubility of tervalent actinides in such compounds which is relevant to the chemistry of nuclear waste immobilization.

Preparation of titanium diboride powder

Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

Raman spectroscopy of polymorphic orthophosphates containing sodium and lanthanide elements

Mixed orthophosphates (Na3Lnx(PO4)y) containing sodium and lanthanide elements have been prepared by several synthetic methods and have been characterized by Raman spectroscopy at both ambient and elevated temperatures, X-ray diffraction, and neutron activation analysis. The elements from La to Gd have been observed to form compounds with the stoichiometry Na3Ln(PO4)2, which exhibit only one type of symmetry. Yttrium and the elements from Tb to Lu form compounds with the stoichiometries Na3Ln(PO4)2 and Na3Ln2(PO4)3. Each compound occurs in several crystal symmetries. One of these, designated as phase γ, appears to be a new phase.

Synthesis and characterization of phosphates containing alkali metals and plutonium or lanthanides

Abstract The compounds Na 3 Pu(PO 4 ) 2 has been synthesized and positively identified for the first time by X-ray diffraction, Raman spectroscopy, and absorption spectrophotometry. The literature of quaternary phosphates containing alkali metals (M) and lanthanides (Ln) or actinides (An) has been critically reviewed. Since the existence of compounds of the type Mn 3 (Ln,An) 2 (PO 4 ) 3 appeared to be questionable, we conducted several replicate experiments with Ln = La to Gd. Our results did not reveal the existence of such compounds.