Tutton Salt Research Articles

SH3 Term in the Submillimeter Electron Spin Resonance of Cobalt Tutton Salt

Submillimeter ESR in cobalt ammonium Tutton salt (NH 4 ) 2 Co(SO 4 ) 2 ·6H 2 O was studied at liquid nitrogen temperature using pulsed high magnetic fields and two submillimeter waves, 337 µm of HCN laser and 119 µm of H 2 O laser. The frequency dependence of the g value was observed. For example, g || at 119 µm was about 2% smaller than that at 337 µm. The observed frequency dependence can be explained by introducing a new S H 3 term in the effective spin Hamiltonian. An extensive theoretical consideration based on the Abragam-Pryce theory shows that the observed shift can satisfactorily be explained quantitatively. This is the first experimental observation of S H 3 term of the iron group ions in ionic crystals.

EPR Of Mn2+ in cobalt potassium selenate hexahydrate tutton salt

physica status solidi (b)Volume 85, Issue 2 p. K103-K105 Short Note EPR Of Mn2+ in cobalt potassium selenate hexahydrate tutton salt S. R. Shukla, S. R. Shukla Department of Physics, P.P.N. College, Kanpur Search for more papers by this authorS. D. Pandey, S. D. Pandey Department of Physics, P.P.N. College, Kanpur Search for more papers by this author S. R. Shukla, S. R. Shukla Department of Physics, P.P.N. College, Kanpur Search for more papers by this authorS. D. Pandey, S. D. Pandey Department of Physics, P.P.N. College, Kanpur Search for more papers by this author First published: 1 February 1978 https://doi.org/10.1002/pssb.2220850254Citations: 4 Kanpur-208001, India. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume85, Issue21 February 1978Pages K103-K105 RelatedInformation

The stereochemistry of Tutton's salts X2[ M(H 2O) 6]( YO 4) 2

Neutron structure determinations have been made of Tutton's salts, X 2[ M(H 2O) 6] ( YO 4) 2, where Y = Se, X = K +, M = Cu 2+; Y = S, X = K +, M = Ni 2+, Cu 2+, Zn 2+; X = Rb +, Cs +, M = Cu 2+. This work has shown that there are extensive hydrogen networks with almost linear hydrogen bonds from [ M(H 2O) 6] 2+ to ( YO 4) 2−. The (H … O) distance increases in the Cu 2+ series for X = K + to Cs + but there is no difference for the potassium copper salts when Y = Se or S. Three different distorted [ M(H 2O) 6] 2+ octahedra were found in the series (orthorhombic, tetragonal with two long and four short, or four long and two short bonds). The interatomic distances from X + to the neighboring O in a distorted XO 8 + dodecahedron increases with increased cation size, implying that the X + polyhedron is maintaining its shape.

EPR of Mn2+ in Tutton Salts

Abstract Electron paramagnetic resonance of divalent Mn2+ ions in the Tutton salts M″M2′ (SO4)2·6 H2O, (M′ =Mg, Fe, Zn, Cd and M′ = Rb, Cs) and CdM2′(SO4)2·6 H2O, (M′ = K, NH4) single crystals has been studied at 298 K. The Mn2+ is found to substitute divalent cation sites. The spectra have been analysed using the spin-Hamiltonian appropriate for rhombic symmetry.

Low-frequency relaxation measurements on cobalt ammonium tutton salt placed in liquid helium and vacuum respectively

A comparison is made between the results of differential susceptibility measurements on cobalt ammonium Tutton salt placed in liquid helium and in vacuum, respectively. Due to ageing effects part of the cobalt ions forms a separate spin system; nevertheless the direct relaxation process τ −1 dir = 0.1 H 4 T s -1 ( H in kOe) is effective in both systems with the same proportionality factor. It is found that the lengthening of the relaxation time in the strong-field range with respect to the direct process is not due to thermal conduction effects but is a result of an internal relaxation process. An anomalous relaxation behaviour at 14 K could be explained by this relaxation process.

Spin quenching and EPR of Mn 2+ in single crystals of nickel salts

An EPR study of Mn 2+ in (NH 4) 2Ni(SeO 4) 2·6H 2O crystals has been reported for the first time at room temperature (≈300 K) and at the X-band. The observations regarding the anisotropic and field dependent linewidths of Mn 2+ in nickel Tutton salts at room temperature are discussed in terms of the spin quenching ideas. Also, the g z -shift in Mn 2+-doped Ni-Tutton salts is attributed to the internal magnetic field at the site of the Mn 2+ ion, caused by the moments induced on Ni 2+ ions.

Proton spin-lattice relaxation in deuterated diluted copper tutton salts

The spin-lattice relaxation time, T 1 I , of the protons in (Cu,Zn)Cs 2(SO 4) 2·6(H,D) 2O was measured. The sample was 94% deuterated and contained 0.5% Cu 2+ ions. The T 1 I measurements were carried out at liquid helium temperatures and at fields in the region from 5–15 kOe. Under these conditions, T 1 I shows a strong dependence on the direction of H 0 with respect to the crystal axes, in the magnetic K 1– K 3 plane. This angular dependence has been accurately determined close to the K 1 and K 3 axes, at 1.4K. Between the angular dependent behaviour of the proton relaxation time and the EPR spectrum of the Cu 2+ ions exists a striking correlation: T 1 I exhibits sharp minima at angles where the frequency distance between the EPR lines is about equal to the proton resonance frequency. The observed temperature dependence in the liquid helium region is weak and can very well be described with a factor (1− P 2 0) −1, where P 0 denotes the electron polarization. The field dependence of T 1 I appears to be between H 1.0 0 and H 1.5 0.

A study of the thermal contact between the nuclear Zeeman system and the electron dipole-dipole interaction system

In order to explain proton spin-lattice relaxation measurements in a deuterated copper Tutton salt [1], we performed a theoretical investigation of the thermal contact between the proton Zeeman system (PZS) and the electron dipole-dipole interaction system (EDDS). The basic process that maintains the contact between these two spin systems is a three-spin process in which one proton spin and two electron spins make a simultaneous transition. We calculated the transition probability of this three-spin process. It was proved that neither electron spin-lattice relaxation nor cross-relaxation are a bottle-neck in the proton spin-lattice relaxation, so the observed relaxation time values are completely determined by this three-spin process. Hence, the contact time between the PZS and the EDDS can be derived directly from the measurements.

EPR of divalent manganese in cobalt ammonium selenate hexahydrate

EPR of Mn 2+ has been studied in cobalt ammonium selenate hexahydrate from ≈ 90 K to ≈ 300 K and the spin-hamiltonian parameters determined. It has been found that replacement of S by Se does not cause much change in the strength and symmetry of the crystal field at the divalent cation site in Tutton salts.

EPR investigations of Mn 2+ in MK 2(SO 4) 2-6H 2O Tutton salt single crystals

EPR investigations have been carried out in Mn 2+ doped isomorphous single crystals of MK 2 (SO 4) 2 -6H 2O Tutton salts, where M = Co, Fe, Mg and Zn, at room and at liquid nitrogen temperature using X-band microwave frequency. Mn 2+ has been found to substitute for M 2+ exhibiting two magnetically inequivalent complexes. The EPR spectra have been analyzed using a spin-hamiltonian of orthorhombic symmetry. The additional features observed in the EPR spectra of Mn 2+ in paramagnetic hosts have been attributed to the magnetic interactions between Mn 2+ and the paramagnetic host ions. The use of an impurity probe (e.g. Mn 2+) to measure the extremely fast spin-lattice relaxation times at higher temperatures is illustrated by estimating T 1 of Co 2+ in CoK 2 (SO 4) 2·6H 2O from the observed linewidths of Mn 2+ in CoK 2(SO 4) 2 -6H 2O.

Observation of the H2T7 Raman spin-lattice relaxation process in three cobalt tutton salts

The Raman spin-lattice relaxation times of three cobalt Tutton salts were determined at liquid-hydrogen temperatures in magnetic fields up to 100 kOe by means of a.c. susceptibility measurements. At weak external fields the temperature and field dependence of τ shows that characteristics of the usual T 9 Raman process. Above H= 10 kOe the time constants decrease upon increasing the magnetic field. It is demonstrated that this decrease has to be attributed to the field-dependent H 2 T 7 Raman process. Numerically the relaxation time constants above 2 kOe can be given as τ −1 = BT 9 J 8 ( θ D/ T) + CH 2 T 7 J 6( θ D/ T) with B=1.7×10 −9K −9s −1, C=6.3×10 −15kOe −2K −7 s −1 and θ D=145 K for Co(NH 4) 2(SO 4) 2.6H 2O; B=2.3×10 t-9 K −9s −1, C=6.5×10 −15kOe −2K −7s −1 and θ D=120 K for CoK 2(SO 4) 2.6H 2O and B=6.2×10 −9K −9s −1, C=2.2×10 −14kOe −2K −7s −1 and θ D=95 K for CoCs 2(SO 4) 2.6H 2O

Spin Reorientation in Manganese Tutton Salt Mn(NH4)2(SO4)2·6H2O

It has been well know that the typical paramagnetic compound manganese Tutton salt shows an antiferromagnetism with a canted weak ferromagnetism below T N =0.175 K. Recent experiments in the temperature region of millidegree have revealed further that another transformation into the other antiferromagnetic state with hidden canting occurs at about 70 mK. A quantitative explanation of this spin reorientation phenomenon is undertaken based on the four-sublattice model. The free energies for the two possible spin structures are calculated by the molecular field approximation from the Hamiltonian which consists of the magnetic dipole interaction, the exchange interaction and the crystalline field potential. It is shown that the spin reorientation can occur for reasonable values of the exchange parameters and for either signs of D . With the use of the exchange parameters which can explain the spin reorientation, the temperature dependences of the sublattice magnetization and the magnetic susceptibilities are calculated.

Covalency effects on the E.S.R. spectra of VO2+in hexaaquo magnesium dihydrogen ethylenediaminetetraacetic acid

The E.S.R. spectra of VO2+ doped in hexa-aquo magnesium dihydrogen ethylenediaminetetra-acetic acid and two magnesium Tutton's salts are studied. VO2+ is found to enter the lattice substitutionally into the Mg sites. Only one set of eight lines is observed and transitions due to other orientations of the V-O bond were not observed. The V-O bond is found to coincide with the Mg-O w1 bond direction. The electric field symmetry at the Mg site is found to be rhombic. The Fermi contact term and the bonding coefficient are evaluated from the spin-Hamiltonian parameters and these values, together with the low value of Az , indicate a high degree of covalency in the Mg(H2O)6 octahedron, brought about by the participation of the water molecules in large scale hydrogen bonding.

A study of the direct spin-lattice relaxation process in three manganese compounds at liquid-hydrogen temperatures

Spin-lattice relaxation times of manganese fluosilicate, manganese Tutton salt and manganese sulphate tetrahydrate were obtained from a.c. susceptibility measurements in magnetic fields up to 50 kOe at liquid-hydrogen temperatures. The direct relaxation process was observed in strong magnetic fields, without the inaccuracies due to the phonon bottleneck which usually influences similar experiments at lower temperatures. The relaxation times of the direct process may be given as τ −1 = A H 2 T, with A = 3.2 × 10 −7, 1.5 × 10 −7 and 1.3 × 10 −7 Oe −2 K −1 s −1 for powdered MnSiF 6.6H 2O, Mn(NH 4) 2(SO 4) 2.6H 2O and MnSO 4.4H 2O, respectively. These constants are compared with predictions based on the Waller-Al'tshuler and the Kronig-Van Vleck interaction mechanism, the latter leading to a reasonable agreement with experiment.

Proton spin-lattice relaxation in diluted copper tutton salts

Measurements are presented of the proton relaxation time in Cu x Zn 1− x Cs 2(SO 4) 26H 2O at liquid-helium temperatures. The results are explained by a thermodynamic model which distinguishes various electron Zeeman systems, and a dipolar interaction system strongly coupled to the proton spin system. The theory gives a quantitatively satisfactory explanation of the complicated behaviour of the proton spin relaxation time as a function of magnetic field and temperature.

Cross relaxation and spin thermodynamics in some diluted copper tutton salts

The dynamics of spin systems in some diluted copper Tutton salts is investigated with the method of pulsed ENDOR. This method is suited particularly to study the fast time-dependent behaviour of the spin temperatures. The dynamics in copper Tutton salts is explained with the introduction of four electron Zeeman systems, one combined electron dipole- dipole and proton Zeeman system and the lattice each with a temperature of its own. The cross-relaxation mechanism is a contact between the electron Zeeman systems and the electron dipole-dipole system. Its rate τ −1 cr can be measured directly. Moreover information is gained about the contact between the proton Zeeman system and the electron dipole-dipole system. The experiments demonstrate that the model of a spherical diffusion barrier, that is often used in the theory of the relaxation of the proton magnetization by paramagnetic impurities, is not valid in our samples.

Spin reorientation in manganese tutton salt Mn(NH4)2(SO4)2⋅6H2O

It has been well know that the typical paramagnetic compound manganese Tutton salt shows an antiferromagnetism with a canted weak ferromagnetism below T N =0.175 K. Recent experiments in the temperature region of millidegree have revealed further that another transformation into the other antiferromagnetic state with hidden canting occurs at about 70 mK. A quantitative explanation of this spin reorientation phenomenon is undertaken based on the four-sublattice model. The free energies for the two possible spin structures are calculated by the molecular field approximation from the Hamiltonian which consists of the magnetic dipole interaction, the exchange interaction and the crystalline field potential. It is shown that the spin reorientation can occur for reasonable values of the exchange parameters and for either signs of D . With the use of the exchange parameters which can explain the spin reorientation, the temperature dependences of the sublattice magnetization and the magnetic susceptibilities are ...

Crystallite size dependence of the spin-lattice relaxation rates of protons in a paramagnetic salt with phonon bottleneck

Proton spin-lattice relaxation times were measured at 4.2 K for varying sample thicknesses in the copper tutton salt CuK 2(SO 4) 2·6H 2O. The relaxation of protons through electrons possessing position dependent phonon bottleneck properties gives rise to a size effect.

ESR of a dilute-Mn tutton salt around 0.1 K

Only one fine structure component with six hfs lines remains to be observed at the lowest temperature region, showing the sign of D to be positive. The intensities of its hfs lines are not equal reflecting the polarization of Mn nuclei and can be used as a thermometer down to 8 mK.

ESR of Cu2+(H2O)6. II. A quantitative study of the dynamic Jahn-Teller effect in copper-doped zinc Tutton's salt

The X-band ESR spectra of 63Cu2+ doped zinc Tutton's salt enriched to 16 at.% in 17O isotope was studied in a single crystal at 20, 77, and 290°K. The powder spectrum of the same material was studied over the temperature range 10–350°K at X band and 120–290°K at Q band. The observed values of the g tensor and 63Cu and 17O hyperfine tensors were found to be strongly temperature dependent except when the magnetic field was parallel to g3, one of the principal axes of the g tensor. The directions of the principal axes of the g tensor and 63Cu hyperfine tensor were shown to be temperature independent, in opposition to the findings of other workers. In the single crystal, marked mI dependent linewidth variations in the 63Cu hyperfine components were observed in the temperature range 14–80°K, except when the external field was parallel to g3. The experimental data are explicable in terms of a dynamic Jahn-Teller effect, in contrast to the previously held assumption that dilute copper Tutton's salt is a static Jahn-Teller system. The energy splittings between the three inequivalent valleys were determined directly from the experimental results and found to be δ1,2 = 75 cm−1, δ1,3 ≃ 450 cm−1. The splittings are discussed in terms of published crystallographic data on Tutton's salts, and a crystal field calculation gave a value of δ1,2/δ1,3 = 1/5 in good agreement with experiment. The rate of intervalley jumping between the lowest two valleys was determined from linewidth measurements and found to be characteristic of an Orbach process, following the law τ = τ0 exp(120/k T). The value of 120 cm−1 is identified with the height of the ``warping'' barrier between valleys 1 and 2. Phonon-assisted tunneling makes no significant contribution to the jumping rate.