A New Oxide Spin Glass System of (1-x) FeTiO3–xFe2O3. I. Magnetic Properties

Ishikawa, Yoshikazu; Saito, Norio; Arai, Masatoshi; Watanabe, Yuji; Takei, Hiroyuki

doi:10.1143/jpsj.54.312

Cited by 64 publications

(105 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hemoilmenite with 80-90% ilmenite content seems the most probable candidate. Indeed, at least some of our susceptibility curves resemble curves measured on synthetic samples of this composition (Ishikawa et al, 1985). Similar χ -T curves have been also reported for some Hawaiian basalts (Kontny et al, 2003;Yamamoto, 2006) where presence of (hemo) ilmenite was demonstrated by microscopic observations.…”

Section: Discussionsupporting

confidence: 88%

“…First break-inslope occurs between 30-50 K, and second around 200 K. Temperature dependences of the coercive force show a similar trend. We propose that feature at ∼200 K is a manifestation of Néel temperature of hemoilmenite which would then contain about 20 mole% of hematite (Ishikawa et al, 1985). Break-in-slope at 30-50 K, on the other hand, is observed in all our samples, except one, and therefore is likely due to titanomagnetite.…”

Section: Discussionmentioning

confidence: 60%

See 1 more Smart Citation

Low-temperature magnetic properties of andesitic rocks from Popocatepetl stratovolcano, Mexico

et al. 2009

View full text Add to dashboard Cite

To contribute to the growing database of magnetic properties of rocks and minerals at cryogenic temperatures, we have measured magnetization, low-field susceptibility, and hysteresis loops as a function of temperature between 2 K (10 K for hysteresis) and 300 K for twelve representative samples from a suite of volcanic rocks of predominantly andesitic composition erupted by the Popocatepetl stratovolcano, Mexico. High temperature susceptibility measurements have yielded Curie points (T C ) mostly between 430 and 550• C, two samples additionally containing a magnetic phase with T C of 300-320• C, and one sample-with 140-170• C. Hysteresis measurements at room temperature have revealed invariably the presence of a low-coercivity mineral with coercive force ranging from 10 to 20 mT. This suggests that NRM of Popocatepetl rocks is carried by an intermediate titanomagnetite of composition between approximately TM04 and TM20. Thermal demagnetization of SIRM given at 2 K displays no evidence for the Verwey transition, further showing that samples are essentially magnetite free. At the same time, an inflection between 30-50 K reported previously for intermediate titanomagnetites (Moskowitz et al., EPSL, 157, 141-149, 1998) is seen in all studied Popocatepetl samples except one. As well, below 50 K the coercive force increases sharply with decreasing temperature reaching up to 100 mT at 10 K. On the other hand, examining the behavior of low-field susceptibility at cryogenic temperatures shows that susceptibility signal is dominated by intermediate titanomagnetites only in a part of our samples. In four out of 12 samples, however, susceptibility signal appears to be due to a hemoilmenite phase containing about 20 mole% of hematite. Caution is thus advised when interpreting low-temperature susceptibility data in terms of magnetic mineralogy.

show abstract

Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 60%

Low-temperature magnetic properties of andesitic rocks from Popocatepetl stratovolcano, Mexico

et al. 2009

View full text Add to dashboard Cite

show abstract

“…This is because the Néel temperature of the ilmenite (end-member of TH phase) is 55 K (Ishikawa and Akimoto, 1985), and the present peak appears to be analogous to a temperature-dependent variation in a weak field magnetization of ILM90 (Fig. 5, modified from Ishikawa et al (1985)). In fact, the EPMA analyses clearly demonstrated that the TH phase of A-5 corresponds to ILM90-94.…”

Section: Low-and High-temperature Magnetic Susceptibilitiesmentioning

confidence: 74%

Possible TCRM acquisition of the Kilauea 1960 lava, Hawaii: failure of the Thellier paleointensity determination inferred from equilibrium temperature of the Fe−Ti oxide

Yamamoto

2006

Earth Planet Sp

View full text Add to dashboard Cite

Natural rock samples may not always be the ideal material for the Thellier-type method as they occasionally result in high paleointensities. The Kilauea 1960 lava, Hawaii, is one such example. Several previous studies have suggested that one of the possible causes for this undesirable behavior is an acquisition of thermochemical remanent magnetization (TCRM) during lava formation. In order to examine this possibility quantitatively, equilibrium temperatures of titanomagnetite grains, which are associated with samples previously subjected to Thellier experiments, are estimated by a Fe-Ti oxide geothermometer. The results show that two specimens from the rock magnetic group giving relatively ideal Thellier paleointensities have clustered equilibrium temperatures of about 800-900 and 700-800• C. In contrast, two swarmed temperatures around 300 and 700• C were observed for the specimen from a group yielding high paleointensities. Although these are semi-quantitative estimates, when the time scales of Fe-Ti interdiffusion and lava cooling are taken into consideration, the last specimen could have acquired the TCRM during its formation. For such specimens, simple calculation predicts that TCRM/TRM (thermoremanent magnetization) ratios could be 1.19-1.72 for the blocking temperature range of 400-480• C, assuming a grain-growth model. The extent of this overestimation (20-70%) is comparable to the magnitude of the observations. It is therefore suggested that attention be paid to titanomagnetite grains with well-developed ilmenite lamellae, as these could be potential sources of overestimations of Thellier paleointensities of up to a few tenths of percentage points.

show abstract

“…The smooth variation of remanences near 100-150 K indicated some impurities in magnetite grains. The curves also showed remanence reductions at 35 and~50 K, which may indicate the existence of magnetic minerals other than magnetite, such as pyrrhotite (Dekkers et al 1989) and the rhombohedral phase of FeTi oxide (Ishikawa et al 1985). The apparent transitions of 50 K were seen in most of the samples.…”

Section: Low-temperature Magnetometrymentioning

confidence: 86%

Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan

Sato

Yamamoto

et al. 2015

Earth Planet Sp

View full text Add to dashboard Cite

This paper reports on the rock-magnetic properties of single zircon crystals, which are essential for future work establishing the reliable paleointensity method using single zircon crystals. Zircon crystals used in this study were sampled from the Nakagawa River, which crosses the Tanzawa tonalitic pluton in central Japan. Rock-magnetic measurements were conducted on 1037 grains of zircons, but many of these measurements are below the limits of the sensitivity of the magnetometers employed. Isothermal remanent magnetizations (IRMs) of 876 zircon crystal are below the practical resolution of this study; we infer that these crystals contain no or only minute quantities of ferromagnetic minerals. The other zircon crystals contain enough magnetic minerals to be measured in the DC SQUID magnetometer. Am 2 (80 zircons), combining the rock-magnetic parameter, we proposed the sample-selection criteria for future study of paleointensity experiments using single zircon crystals. In the case that the samples had high coercivity (B c ) values (>10 mT) or high M NRM /M IRM values (>~0.1), main remanence carriers are probably pyrrhotite and these samples are inappropriate for the paleointensity study. In the case that the samples had low B c values (<10 mT) and low M NRM /M IRM values (<~0.1), main remanence carriers seem to be nearly pure magnetite with pseudo-single-domain grain sizes, and these samples are expected to appropriate for the paleointensity study. Total thermoremanent magnetization (TRM) acquisition experiments were also carried out for 12 samples satisfying the above criteria. The TRM intensity was comparable with that of NRM, and a rough estimation of the paleointensity using NRM/TRM ratios shows field intensities consistent with the average geomagnetic field intensity at the Tanzawa tonalitic pluton for last 5 Myr.

show abstract

A New Oxide Spin Glass System of (1-x) FeTiO₃–xFe₂O₃. I. Magnetic Properties

Cited by 64 publications

References 21 publications

Low-temperature magnetic properties of andesitic rocks from Popocatepetl stratovolcano, Mexico

Low-temperature magnetic properties of andesitic rocks from Popocatepetl stratovolcano, Mexico

Possible TCRM acquisition of the Kilauea 1960 lava, Hawaii: failure of the Thellier paleointensity determination inferred from equilibrium temperature of the Fe−Ti oxide

Rock-magnetic properties of single zircon crystals sampled from the Tanzawa tonalitic pluton, central Japan

Contact Info

Product

Resources

About