W. Kwestroo

Compounds in the system BaOY2O3

Abstract Starting with BaO and Y 2 O 3 , four compounds are found in the BaOY 2 O 3 system. At high temperatures (above 1200°C) two compounds mentioned in literature are found: Ba 3 Y 4 O 9 and BaY 2 O 4 . Heating the oxidic mixtures at 900°C results in the formation of a new compound Ba 2 Y 2 O 5 . This compound is transformed at 1000°C into another new compound: Ba 4 Y 2 O 7 . X-ray data of the four compounds are given in detail.

Hydrates of manganese (II) oxalate

Abstract In addition to the monoclinic ∝-dihydrate, it has now proved possible to prepare a second dihydrate, hitherto unknown. This compound, having an orthorhombic unit cell, proves to be the more stable modification of the dihydrates. For the trihydrate as well as for the anhydrous salt, orthorhombic unit cells were found. Prescriptions for the preparation of each of the hydrates are given. Some details are added about particle size, thermal decomposition and stability of the compounds, together with crystallographic and X-ray data.

Compounds in the system BaO In2O3

Abstract The occurrence of compounds in the system BaOIn2O3 has been investigated. In addition to the already known compounds BaIn2O4 and Ba4In6O13, three new compounds were found: Ba2In2O5, Ba3In2O6 and Ba5In2O8. Ba2In2O5 has a simple, perovskite-like X-ray diagram, which however, could not be indexed. Ba3In2O6 and Ba5In2O8 have tetragonal body-centered unit cells with a = 4.1913 A , c = 21.6693 A and a = 4.1742 A , c = 29.431 A respectively. Ba3In2O6 reacts with most air to form a hydrogarnet: Ba3In2(OH)12.

Spinel phase in the system MgOFe2OAl2O3

Abstract The three component system MgOFe 2 OAl 2 O 3 has been investigated at 1250°C and at 1400°C. The binary parts of this system, already described some twenty years ago, are reviewed and completed. The ternary diagram shows a broad spinel area: this area increases with increasing temperatures. Our preparations do not contain Fe 2+ ions, as was ascertained by analytical methods and by d.c. resistivity measurements. The resistivity has a fairly high value. The physical properties are roughly in agreement with the properties already found in systems investigated previously. Substituting Al 3+ ions for Fe 3+ ions in the spinel phase lowers the value of the magnetic saturation and the Curie temperature. An increasing amount of Fe 2 O 3 in the spinel phase increases the magnetic saturation and the Curie temperature. Samples with the composition of a mineral called “hoegbomite” have been investigated and the possible structure of this mineral is discussed.

Compounds in the system BaOSc2O3

Abstract The occurrence of compounds in the system BaOIn2O3 has been investigated. In addition to the already known compounds BaIn2O4 and Ba4In6O13, three new compounds were found: Ba2In2O5, Ba3In2O6 and Ba5In2O8. Ba2In2O5 has a simple, perovskite-like X-ray diagram, which however, could not be indexed. Ba3In2O6 and Ba5In2O8 have tetragonal body-centered unit cells with a = 4.1913 A , c = 21.6693 A and a = 4.1742 A , c = 29.431 A respectively. Ba3In2O6 reacts with most air to form a hydrogarnet: Ba3In2(OH)12.

Basic lead nitrates

Abstract The phases in the system Pb(NO 3 ) 2 -Pb(OH) 2 were investigated by X-ray diffraction methods. Four one-phase products were found: Pb(NO 3 ) 2 ·Pb(OH) 2 ; 2Pb(NO 3 ) 2 ·5Pb(OH) 2 ; Pb(NO 3 ) 2 ·3Pb(OH) 2 and Pb(NO 3 ) 2 ·5Pb(OH) 2 . The compound Pb(NO 3 ) 2 ·3Pb(OH) 2 can be prepared only in more dilute solutions. The composition of these compounds was confirmed by chemical analysis. When the compounds are heated up to 300°C, some water is lost and the X-ray diagrams are changed, but the Pb:NO 3 ratio does not alter essentially. The interplanar spacings and the X-ray intensities of the four basic lead nitrates are given.

The preparation of ultra pure lead oxide

Abstract A method is described for preparing very pure PbO from lead acetate with ammonia at room temperature. Preparation in polyethylene vessels gives red PbO, which contains 1 ppm. silica and about 10 ppm. carbon. As more than 20 ppm. Si prevent the spontaneous recrystallisation in water from yellow orthorhombic to red tetragonal PbO, preparation in silica vessels gives yellow PbO, which contains 100 ppm. silica and 1000 ppm. carbon. Results of spectrochemical and mass spectrometric analysis are included.

The hydrogarnets Ba3In2(OH)12 and Ba3Sc2(OH)12

Two new hydrogarnets Ba/sub 3/In/sub 2/(OH)/sub 12/ and Ba/sub 3/Sc/sub 2/(OH)/sub 12/ have been prepared: (a) by heating the mixed hydroxides in an autoclave at 400/sup 0/C for 24 hours and (b) by precipitating a mixture of soluble salts with very concentrated (12N) NaOH and refluxing the reaction product. Efforts to prepare other Ba hydrogarnets by these methods failed. X-ray data and some chemical properties of the new compounds are added.

Influence of impurities on the formation of red and yellow PbO

Abstract The influence of silica and other impurities, as well as of reactant concentrations, upon the course of the reaction between lead acetate and ammonium hydroxide, and upon the identity of the reaction products, are described. The immediate reaction product is a white precipitate consisting of either Pb(CH 3 COO) 2 ·2Pb(OH) 2 , or Pb(OH) 2 , or a mixture of these compounds, depending upon the presence or absence of impurities, and upon reactant concentrations. In contact with the supernatant liquid the basic acetate or hydroxide converts spontaneously into a green precipitate which has the orthorhombic structure of yellow lead oxide. After decantation and drying the result is red, tetragonal lead oxide if certain impurities are absent. The elements Si, Ge, P, As, Sb, Se, Te, Mo and W, when present in the precipitation solution as anions at concentrations as low as 10–100 ppm prevent the transformation of the orthorhombic into the tetragonal structure. The result is then yellow orthorhombic lead oxide. By application of these findings, it is possible to prepare ultra-pure red oxide, or the yellow oxide only slightly contaminated with one of the specified elements, as desired.

Basic lead acetates

Abstract The occurrence of basic lead acetates was investigated by X-ray diffraction diagrams taken from dried samples of lead acetate-lead oxide reaction mixtures. Two compounds were found: 3Pb(CH 3 COO) 2 ·PbO·H 2 O and Pb(CH 3 COO) 2 ·2PbO·H 2 O. A compound Pb(CH 3 COO) 2 ·PbO was not detected. The interplanar spacings and X-ray intensities for the two basic acetates are given. The data for anhydrous lead acetate, Pb(CH 3 COO) 2 , are included.