Controversy on the Free Energy of Formation of CaO Additional Evidence in Support of Thermochemical Data

The standard free energies of formation of CaO derived from a variety of high-temperature equilibrium measurements made by seven groups of experimentalists are significantly different from those given in the standard compilations of thermodynamic data. Indirect support for the validity of the compiled data comes from new solid-state electrochemical measurements using single-crystal CaF2 and SrF2 as electrolytes. The change in free energy for the following reactions are obtained: CaO + MgF2 --> MgO + CaF2 Delta G degrees = -68,050 -2.47 T(+/-100) J mol(-1) SrO + CaF2 --> SrF2 + CaO Delta G degrees = -35,010 + 6.39 T (+/-80) J mol(-1) The standard free energy changes associated with cell reactions agree with data in standard compilations within +/- 4 kJ mol(-1). The results of this study do not support recent suggestions for a major revision in thermodynamic data for CaO.

Ei sanat salahan joua : fennistiikan murteenkeruun historiaa 1868 - 1925

Pro gradu -tutkielmani käsittelee Suomen murteiden sanakirjan taustaksi kerätyn Suomen murteiden sana-arkiston kartuttamisen historiaa; fennistisen murteenkeruun alkuvaiheita. Lähestyn murresanakirjan pitkää hanketta tutkimus- ja kulttuurihistoriallisesta näkökulmasta. Kansankielen sanakirja on fennistiikan merkittävimpiä tutkimushankkeita. Suo-men kielen vanhojen pitäjänmurteiden sanasto on ällistyttävän laaja aineisto, jonka keräämiseen ja julkaisemiseen on kulunut toista vuosisataa, ja sanakirjan toimitustyö jatkuu edelleen. Kansanmurteemme sisältävät paitsi kielitieteellisesti mielenkiintoista aineistoa myöskin runsaasti tietoa agraarisen elinkeinorakenteen aikakaudelta. Dialektologia ja kansatiede kulkevat käsikkäin. Murresanakirja on niin ollen merkittävä kansallinen omaisuus, jonka arvo koko suomalaiselle yhteiskunnalle on eittämättä suuri. Murteiden sanakirjan syntysanat on ajoitettavissa vuoteen 1868, vaikka toki fennistiikassa oli leksikografisia pyrintöjä jo ennen sitä (mm. Lönnrotin Suomalais-ruotsalainen sanakirja). Sanakirjahankkeessa on hahmotettavissa kolme vaihetta, joita kutsun ryhdistäytymisiksi. Nämä tapahtuivat noin vuosina 1896, 1916 ja 1925. Valotan työni aluksi hieman kansallisten tieteiden ja 1800-luvun alun aatehistoriallista taustaa (luku 2), jonka jälkeen tutkin murresanakirjahankkeen alkuvaiheita ja ensimmäisten sanastonkeruiden käynnistymistä (luku 3). Käsittelen kutakin hankkeen organisatorista muutosvaihetta ja hallinnollisten puitteiden kehittymistä luvuissa 4-6. Lopuksi pohdin murresanakirjan ja murteenkeruun historiallista merkitystä fennistiikalle ja yhteiskunnalle (luku 7). Tutkimukseni lähteinä on oppihistoriallista kirjallisuutta sekä murteiden keruusta vastanneiden yhteisöjen asiakirjoja. Erityisen kiinnostaviksi osoittautuivat Kotimaisten kielten tutkimuskeskuksessa säilytettävät sanakirjahankkeen hallinnolliset asiakirjat 1916-1925. Tuon esiin varhaisempiakin pöytäkirjamainintoja. Hankkeen alussa Suomalaisen Kirjallisuuden Seuran Kielitieteellinen Osakunta ja Kotikielen Seura keräsivät ensimmäisiä sanastokokoelmia. Tämän jälkeen ensimmäinen ryhdistäytyminen tapahtui vuodesta 1896 lähtien, jolloin Suomalaisen Kirjallisuuden Seura otti vastuun hankkeesta, E. N. Setälän tunnettua sanakirjaohjelmaa ja E. A. Ekmanin Suomen kielen keräilysanastoa noudattaen. Keruu oli kuitenkin liian hidasta, joten 1916 perustettiin Suomen kielen sanakirjaosakeyhtiö, jotta toimintaan saataisiin enemmän varoja. Ensimmäinen maailmansota ja sisällissota kuitenkin romahduttivat rahan arvon, ja kolmannen kerran hanke jouduttiin organisoimaan uudelleen vuonna 1925, Sanakirjasäätiön muodossa. Vuonna 1976 Sanakirjasäätiö liittyi Kotimaisten kielten tutkimuskeskukseen. Kansanmurteiden keräämisessä korostuu kaikissa keruun vaiheissa kaksi asiaa. Ensinnäkin sanastuksella oli aina kiire. Vanhat murteet olivat katoamassa, ja ne piti saada nopeasti talteen. Tähän kiinnitettiin huomiota jo varhain, ja vielä 1900-luvun loppupuoliskollakin, kun keruuhanke hiljalleen saatiin loppuunviedyksi. Toiseksi sanakirjahanke on aina joutunut elämään kädestä suuhun, toisin sanoen taloudelliset puitteet ovat sanelleet keruumahdollisuudet. Vakaalle taloudelliselle pohjalle hanke pääsi vasta 1930-luvulla Sanakirjasäätiön aikana, jolloin siihen alettiin saada valtion rahoitusta. Murresanakirjahankkeen läpi kulkee punaisena lankana kansallisromanttinen innostus ja isänmaallis-tieteellinen pyrkimys suomen kirjakielen kehittämiseen, joka vielä 1800-luvun puolivälissä oli meneillään. Kansalliset tieteet lujittivat itsenäistymistä ja suoma-laistumista. Aatehistorian kautta sanakirjahanke asettuu laajempaan yhteyteen. Avainsanat: tutkimushistoria, suomen kielen murteet, murteenkeruu, dialektologia, suomen murteiden sanakirja, fennistiikan oppihistoria, leksikografia, kansalliset tieteet, Suomalaisen Kirjallisuuden Seura, Kotikielen Seura, Suomen kielen sanakirjaosakeyhtiö, Sanakirjasäätiö

Portrait of Samuel Mayer Ehrenberg ( 1773 - 1853 ).

This painting is in dedication " in honor of Meyer Ehrenberg by his students" as stated on a scroll held by the sitter. The scroll is dated October 7, 1820 and is followed by a list of names in two columns: (M.Ehrenberg, P.Ehrenberg, B. Ehrenberg, M.Imanuel M.Balke, B.Meier, L.Franck, M. Cohen, W.Fraenkel, M. Chohns, P.Goldschmidt, J.Lippoa, A. Nathan, M.Kramer, J.Fraenkel, M.Goldschmidt.) Ehrenberg was the founder of the first modern Jewish Day School in Germany, at Wolfenbuettel. Ehrenberg was the great-grandfather of the Jewish Theologian Franz Rosenzweig.

Portrait of Heinrich Stahl (1868-1942 ).

H.Stahl was the last president of the Jewish Community in Berlin. He is seated in a chair with wooden arm supports. He seems a small man, an impression emphasized by a large expanse of plain, tan background. The facial expression is tense, with deeply furrowed brows.

[The Rosenthal family from Münchholzhausen] 1868-1957

Vital records (originals and translations) and a family tree of the descendents of the cobbler Moses Rosenthal (1820-1896) and his wife Hannchen Stern (1815-1868) from Münchholzhausen, Germany.

Phosphorus Partition between Liquid Steel and CaO-SiO2-P2O5-MgO Slag Containing Low FeO

CaO-SiO2-FeOx-P2O5-MgO bearing slags are typical in the basic oxygen steelmaking (BOS) process. The partition ratio of phosphorus between slag and steel is an index of the phosphorus holding capacity of the slag, which determines the phosphorus content achievable in the finished steel. The influences of FeO concentration and basicity on the equilibrium phosphorus partition ratios were experimentally determined at temperatures of 1873 and 1923 K, for conditions of MgO saturation. The partition ratio initially increased with basicity but attained a constant value beyond basicity of 2.5. An increase in FeO concentration up to approximately 13 to 14 mass pet was beneficial for phosphorus partition.

Phase Relations in the System CaO-Fe2O3-Y2O3 at 1273 K and Compatibility Between Y1-xCaxFeO3-0.5x and Stabilized Zirconia

Phase relations in the system CaO-Fe2O3-Y2O3 in air (P-O2/P-o = 0.21) were explored by equilibrating samples representing eleven compositions in the ternary at 1273 K, followed by quenching to room temperature and phase identification using XRD. Limited mutual solubility was observed between YFeO3 and Ca2Fe2O5. No quaternary oxide was identified. An isothermal section of the phase diagram at 1273 K was constructed from the results. Five three-phase regions and four extended two-phase regions were observed. The extended two-phase regions arise from the limited solid solutions based on the ternary oxides YFeO3 and Ca2Fe2O5. Activities of CaO, Fe2O3 and Y2O3 in the three-phase fields were computed using recently measured thermodynamic data on the ternary oxides. The experimental phase diagram is consistent with thermodynamic data. The computed activities of CaO indicate that compositions of CaO-doped YFeO3 exhibiting good electrical conductivity are not compatible with zirconia-based electrolytes; CaO will react with ZrO2 to form CaZrO3.

Behavior of Ca(OH)2/CaO pellet under dehydration and hydration

With construction of a thermochemical energy conversion prototype system to store solar heat, thermal dissociation of pellets of Ca(OH)2 and hydration of CaO have been investigated in some detail for its application to the system. The inorganic substance is very attractive as a material for long term heat storage, but molar density changes associated with the reaction are fairly large. Therefore, this factor has been taken into account in the kinetic equation. The importance of additives and pellet size has been discussed considering reactivity and strength of pellets. An analysis has been attempted when chemical reaction is important. The deformation of pellets was observed during hydration.

Phase-relations in the system CAO-SIO2-ZRO2 AT 1573-K

Zirconia-based solid electrolytes with zircon (ZrSiO4) as the auxiliary electrode have been suggested of sensing silicon concentrations in iron and steel melts. A knowledge of phase relations in the ternary system MO-SiO2-ZrO2 (M = Ca, Mg) is useful for selecting an appropriate auxiliary electrode. In this investigation, an isothermal section for the phase diagram of the system CaO-SiO2ZrO2 at 1573 K has been established by equilibrating mixtures of component oxides in air, followed by quenching and phase identification by optical miroscopy, energy disperse analysis of X-rays (EDAX) and X-ray diffraction analysis (XRD). The equilibrium phase relations have also been confirmed by computation using the available thermodynamic data on condensed phases in the system. The results indicate that zircon is not in thermodynamic equilibrium with calcia-stabilized zirconia or calcium zirconate. The silica containing phase in equilibrium with stabilized zirconia is Ca3ZrSi2O9. Calcium zirconate can coexist with Ca3ZrSi2O9 and Ca2SiO4.

Phase equilibria in the system CaO-CoO-SiO2 and Gibbs energies of formation of the quaternary oxides CaCoSi2O6, Ca2CoSi2O7, and CaCoSiO4

Phase relations in the pseudoternary system CaO-CoO-SiO2 have been established at 1323 K. Three quaternary oxides were found to be stable: CaCoSi2O6 with clinopyroxene (Cpx), Ca2CoSi2O7 with melilite (Mel), and CaCoSiO4 with olivine (Ol) structures. The Gibbs energies of formation of the quaternary oxides from their component binary oxides were measured using solid-state galvanic cells incorporating yttria-stabilized zirconia as the solid electrolyte in the temperature range of 1000-1324 K. The results can be summarized as follows: CoO (rs) + CaO (rs) + 2SiO(2) (Qtz) --> CaCoSi2O6 (Cpx), Delta G(f)(0) = -117920 + 11.26T (+/-150) J/mol CoO (rs) + 2CaO (rs) + 2SiO(2) (Qtz) --> Ca2CoSi2O7 (Mel), Delta G(f)(0) = -192690 + 2.38T (+/-130) J/mol CoO (rs) + CaO (rs) + SiO2 (Qtz) --> CaCoSiO2 (Ol), Delta G(f)(0) = -100325 + 2.55T (+/-100) J/mol where rs = rock salt (NaCl) structure and Qtz = quartz. The uncertainty limits correspond to twice the standard error estimate. The experimentally observed miscibility gaps along the joins CaO-CoO and CaCoSiO4-Co2SiO4 were used to calculate the excess free energies of mixing for the solid solutions CaxCo1-xO and (CayCo1-y)CoSiO4:Delta G(E) = X(1 - X)[31975X + 26736 (1 - X)] J/mol and Delta G(E) = 23100 (+/-250) Y(1 - Y) J/mol. A T-X phase diagram for the binary CaO-CoO was computed from the thermodynamic information; the diagram agrees with information available in the literature. The computed miscibility gap along the CaCoSiO4-Co2SiO4 join is associated with a critical temperature of 1389 (+/-15) K. Stability fields for the various solid solutions and the quaternary compounds are depicted on chemical-potential diagrams for SiO2, CaO, and CoO at 1323 K.

The CaO-SrO-CuO-O-2 system: Phase equilibria and thermodynamic properties at 1123 K

Phase relationships in the CaO-SrO-CuO system in pure oxygen at 1.01 x 10(5) Pa pressure were determined by equilibrating different compositions at 1123 K for similar to 120 h and analyzing the phases present in the quenched samples using X-ray diffraction (XRD), optical and scanning electron microscopy, and energy dispersive analysis of X-rays (EDAX). Four solid solution series were observed in the system, The CawSr1-wO monoxide solid solution with rock-salt structure was found to exhibit an asymmetric miscibility gap, The mixing properties of the monoxide system were deduced using a subregular solution model, For the (CaxSr1-x)(2)CuO3 series, a complete solid solution range with orthorhombic space group Immm was obtained. Calcium substituted for strontium up to 68 at. % in SrCuO2+delta and 51.5 at. % in Sr14Cu24O41-delta. The tie lines between the solid solutions were determined accurately, The activity-composition relations in (CaxSr1-x)(2)CuO3, CaySr1-yCuO2+delta, and (Ca2Sr1-z)(14)Cu24O41-delta solid solutions were determined from experimental tie lines. Activities in the (CaxSr1-x)(2)CuO3 and CaySr1-yCuO2+delta series were close to the predictions of the Temkin model, The behavior of the (CazSr1-(z))(14)Cu24O41-delta solid solution was more complex, with the activity of SrCu(24/14)O-(41-delta/14) exhibiting both positive and negative deviations from ideality. Gibbs energy of formation of the CaCuO2+delta metastable phase at 1123 K was deduced from an analysis of the phase diagram.

Dielectric Relaxation in CaO-Bi2O3-B2O3 Glasses

Glasses in the system CaO-Bi2O3-B2O3 (in molar ratio) have been prepared using melt-quenching route. Ion transport characteristics were investigated for this glass using electric modulus, ac conductivity and impedance measurements. The ac conductivity was rationalized using Almond-West power law. Dielectric relaxation has been analyzed based on the behavior of electric modulus behavior. The activation energy associated with the electrical relaxation determined from the electric modulus spectra was found to be 1.76 eV, close to that the activation energy for dc conductivity (1.71 eV) indicating that the same species took part in both the processes. The stretched exponent beta (0.5-0.6) is invariant with temperature for the present glasses.

Mass spectrometric and electrochemical studies of thermodynamic properties of liquid and solid phases in the CaO Al2O3 system

The activities of CaO and Al2O3 in lime-alumina melts were studied by Knudsen cell-mass spectrometry at 2060 K. Emf of solid state cells, with CaF2 as the electrolyte, was measured from 923 to 1223 K to obtain the free energies of formation of the interoxide compounds. The results are critically evaluated in the light of data reported in the literature on phase equilibria, activities in melts, and stabilities of compounds. A coherent set of data is presented, including the previously unknown free energy of formation of CaO.6Al2O3 and the temperature dependence of activities in the liquid phase.

Phase relations in the system SrO-Y2O3-CuO-O2 and CaO-Y2O3-CuO-O2 at 1173 K

Phase relations in the systems SrO-Y2O3-CuO-O2 and CaO-Y2O3-CuO-O2 at 1173 K were established by equilibrating different compositions in flowing oxygen gas at a pressure of 1.01 × 105 Pa. The quenched samples were examined by optical microscopy, X-ray diffraction (XRD), energy dispersive analysis of X-rays (EDAX), and electron spin resonance (ESR). In the system SrO-Y2O3-CuO-O2, except for the limited substitution of Y3+ for Sr2+ ions in the ternary oxide Sr14Cu24O41, no new quaternary phase was found to be stable. The compositions corresponding to the solid solution Sr14−xYxCu24O41 and the compound SrCuO2+δ lie above the plane containing SrO, Y2O3, and CuO,displaced towards the oxygen apex. However, in the system CaO-Y203-CuO-O2 at 1173 K, all the condensed phases lie on the plane containing CaO, Y203, and CuO, and a new quaternary oxide YCa2Cu306.s is present. The quaternary phase has a composition that lies at the center of the nonstoichiometric field of the analogous phase YBa2Cu307_~ in the BaO-Y203-CuO-O2 system. The compound YCa2Cu306.s has the tetragonal structure and does not become superconducting at low temperature. Surprisingly, phase relations in the three systems CaO-Y203-CuO-O2, SrO-Y203-CuO-O2, and BaO-Y203-CuO-O2 are found to be quite different.

Phase equilibria in the system NiO-CaO-SiO2 and Gibbs energy of formation of CaNiSi2O6

Phase relations in the pseudoternary system NiO-CaO-SiO2 at 1373 K are established. The coexisting phases are identified by X-ray diffraction and energy-dispersive X-ray analysis of equilibrated samples. There is only one quaternary oxide CaNiSi2O6 with clinopyroxene structure. The Gibbs energy of formation of CaNiSi2O6 is measured using a solid state galvanic cell incorporating stabilized zirconia as the solid electrolyte in the temperature range of 1000 to 1400 K:Pt, Ni + SiO2 + CaSiO3 + CaNiSi2O6 \ (Y2O3)ZrO2 \ Ni + NiO, Pt From the electromotive force (emf) of the cell, the Gibbs energy of formation of CaNiSi2O6 from NiO, SiO2, and CaSiO3 is obtained. To derive the Gibbs energy of formation of the quaternary oxide from component binary oxides, the free energy of formation of CaSiO, is determined separately using a solid state cell based on single crystal CaF2 as the electrolyte: Pt, O-2, CaO + CaF2 \ CaF2 \ CaSiO3 + SiO2 + CaF2, O-2, Pt The results can be expressed by the following equations: NiO (r.s) + CaO (r.s) + 2SiO(2) (qz) --> CaNiSi2O6 (pyr) Delta G degrees = -115,700 + 10.63T (+/-100) J mol(-1) CaO (r.s) + SiO2 (qz) --> CaSiO3 (wol) Delta G degrees = -90,030 -0.61T (+/-60) J mol(-1).